Back to the future! Selected bone and soft tissue neoplasms with shared genetic alterations but differing morphological and immunohistochemical phenotypes

Bone and soft tissue tumors (BST) are a highly heterogeneous group largely classified by their line of differentiation, based on their resemblance to their normal counterpart in adult tissue. Yet, rendering a specific diagnosis can be challenging, primarily due to their rarity and overlapping histopathologic features or clinical presentations. Over the past few decades, seemingly histogenetic-specific gene fusions/translocations and amplifications have been discovered, aiding in a more nuanced classification, leading to well-established objective diagnostic criteria and the development of specific surrogate ancillary tests targeting these genetic aberrations (e.g., immunohistochemistry). Ironically, the same research also has revealed that some specific tumor subtypes may be the result of differing and often multiple gene fusions/translocations, but, more interestingly, identical gene fusions may be present in more than one phenotypically and biologically distinct neoplasm, sometimes with entirely different clinical behavior. Prime examples include, EWSR1::ATF1 and, less commonly, EWSR1::CREB1 gene fusions present in both clear cell sarcoma, a malignant high-grade tumor with melanocytic differentiation, and angiomatoid fibrous histiocytoma, a mesenchymal neoplasm of intermediate malignancy with a generally indolent course. Similarly, MDM2 amplification, once deemed to be pathognomonic for atypical lipomatous tumor/well differentiated and dedifferentiated liposarcoma, has been documented in a range of additional distinct tumors, including low grade osteosarcomas (e.g. low grade central and surface parosteal) and high-grade intimal sarcomas, amongst others. Such findings reinforce the importance of careful attention to morphological and clinicoradiological features and correlation with molecular testing before rendering a specific diagnosis. Future classification systems in BST neoplasms cannot be solely based on molecular events and ideally will balance morphologic features with molecular analysis. Herein, we provide a narrative literature review of the more common BST neoplasms with shared genetic events but differing demographics, morphology, immunophenotype, and clinical behavior, re-emphasizing the importance of the hematoxylin and eosin slide and the "eye" of the practicing pathologist.

Atypical lipomatous tumor/well differentiated liposarcoma and related mimics with updates. When is molecular testing most cost-effective, necessary, and indicated?

The classification and work-up of adipocytic neoplasms remains challenging and sometimes controversial. Since its initial description by Dr. Enterline, the variety of subtypes and morphological appearances considered to represent the spectrum of atypical lipomatous tumor/well differentiated liposarcoma (ALT/WDL) has expanded, resulting in significant morphologic overlap with other entities, including the recently described atypical spindle cell/pleomorphic lipomatous tumor (ASPLT), conventional spindle cell/pleomorphic lipoma (SPL), and so-called "low-grade" forms of dedifferentiated liposarcoma (DL). Nevertheless, the distinction of most examples of ALT/WDL from lipomas/lipoma-like lesions is easily performed on routine histologic examination but can be problematic if the characteristic atypical cells are poorly represented, particularly in small biopsy specimens, obscured by other cellular elements (inflammation), or simply not recognized. The discovery that lipomatous tumors harbor specific and unique karyotypes and molecular events has resulted in ancillary tests that can help provide more accurate diagnoses, especially in less-than-optimal scenarios. Confirmation of MDM2 immunohistochemical over-expression and detection of the MDM2 gene rearrangement via fluorescent in situ hybridization (FISH) have proven particularly reliable and useful. While FISH analysis for MDM2 gene amplification may be helpful for confirming (or excluding) ALT/WDL, it also can lead to overutilization and overdependence. Furthermore, a small subset of otherwise typical ALT/WDL lack MDM2 gene amplification, employing alternative molecular pathways. The recent recognition of ASPLT has introduced a tumor easily mistaken morphologically for ALT/WDL, often exhibiting bizarre and pleomorphic lipoblasts, but lacking the underlying molecular abnormalities and subsequent risk of dedifferentiation. ASPLT also have overlapping features with the better-established SPL but with a greater tendency to locally recur and more frequent involvement of the distal extremities. The precise criteria separating cellular forms of ALT from what some consider "low grade" forms of DL remains controversial and inconsistently applied, even among individual pathologists within institutions. Given their underlying shared cytogenetic abnormality, molecular testing has no utility in this distinction. Herein is a comprehensive historical overview of ALT/WDL, with updates on its distinction from other similar lipomatous tumors and DL, including practical evidence-based criteria for the appropriate cost-effective use of MDM2 testing.

Keeping it real: Merging traditional and contemporary practices in musculoskeletal pathology: A special issue of neoplastic and non-neoplastic bone and soft tissue pathology

There is no shortage of comprehensive review articles on bone and soft tissue pathology, almost always representing a regurgitation of the literature with little to no guidance on personal "best practices," recommended applications of ancillary testing, and alternative points of view. This special issue of Human Pathology uniquely unites evidence-based medicine, where appropriate, with the collective personal experiences of a wide range of accomplished pathologists from varying institutions and backgrounds, addressing problematic areas, updated and sometimes imperfect classification systems, and their personal preferences for cost-effectively incorporating ancillary testing. For the preponderance of general pathologists (and specialists), whether academic or non-academic, non-neoplastic musculoskeletal diseases represent a far higher percentage of their practice than bone and soft tissue neoplasia. One of the most common frozen sections performed at many hospitals throughout the USA is revision arthroplasty, relying on the pathologist to help determine the presence (or absence) of periprosthetic joint infection, largely based on the hematoxylin & eosin (H&E) slide. Not every institution has access to the latest molecular techniques; fortunately, many of the current immunohistochemical antibodies serve as reliable surrogate markers of genetic mutations, allowing for cheaper but accurate diagnoses, when deemed necessary. Furthermore, molecular testing is often not necessary to establish a specific diagnosis, even among neoplasms with known underlying genetic abnormalities. It must be remembered that most bone and soft tissue tumors were recognized and classified correctly, before we uncovered and understood, among a subset, their underlying and unique molecular aberrations. Perhaps not surprisingly, in some cases, more than one molecular pathway may lead to the same histologic tumor subtype. Less commonly, an identical genetic driver/fusion may result in immunophenotypically and biologically distinct neoplasms, sometimes with entirely different clinical behaviors. "Dedifferentiation," a concept recognized among a variety of bone and soft tissue neoplasms, including but not limited to chondrosarcoma, parosteal osteosarcoma, and liposarcoma, needs to be objectively reassessed, particularly for liposarcoma. The following reviews attempt to address the above concepts, re-emphasizing the important role the practicing pathologist continues to (and must) play in the differential diagnoses of neoplastic and non-neoplastic musculoskeletal diseases.

Osteoid osteomas of the hands and feet: a series of 71 cases

Osteoid osteomas typically arise in the long bones of extremities. Patients often report pain relieved by NSAIDS, and radiographic findings are often sufficient for diagnosis. However, when involving the hands/feet, these lesions may go unrecognized or misdiagnosed radiographically due to their small size and prominent reactive changes. The clinicopathologic features of this entity involving the hands and feet are not well-described. Our institutional and consultation archives were searched for all cases of pathologically confirmed osteoid osteomas arising in the hands and feet. Clinical data was obtained and recorded. Seventy-one cases (45 males and 26 females, 7 to 64 years; median 23 years) arose in the hands and feet, representing 12% of institutional and 23% of consultation cases. The clinical impression often included neoplastic and inflammatory etiologies. Radiology studies demonstrated a small lytic lesion in all cases (33/33), the majority of which had a tiny focus of central calcification (26/33). Nearly, all cases demonstrated cortical thickening and/or sclerosis and perilesional edema which almost always had an extent two times greater than the size of the nidus. Histologic examination showed circumscribed osteoblastic lesions with formation of variably mineralized woven bone with single layer of osteoblastic rimming. The most common growth pattern of bone was trabecular (n = 34, 48%) followed by combined trabecular and sheet-like (n = 26, 37%) with only 11 (15%) cases presenting with pure sheet-like growth pattern. The majority (n = 57, 80%) showed intra-trabecular vascular stroma. No case showed significant cytology atypia. Follow up was available for 48 cases (1-432 months), and 4 cases recurred. Osteoid osteomas involving the hands and feet follow a similar age and sex distribution as their non-acral counterparts. These lesions often present with a broad differential diagnosis and may initially be confused with chronic osteomyelitis or a reactive process. While the majority of cases have classic morphologic features on histologic exam, a small subset consists solely of sheet-like sclerotic bone. Awareness that this entity may present in the hands and feet will help pathologists, radiologists, and clinicians accurately diagnose these tumors.

Fine-needle aspiration biopsy diagnosis of histiocyte-rich rhabdomyoblastic tumor (inflammatory leiomyosarcoma): A case report

Histiocyte-rich rhabdomyoblastic tumor (HRRMT) is an exceedingly rare soft tissue tumor of primitive myogenic differentiation. We report herein a case involving the soft tissue in the left lateral peri-scapular region in a 68-year-old female with a 2-month history of a non-painful soft tissue mass. Ultrasound revealed a solid, ovoid subcutaneous mass lesion that lacked significant internal vascularity. Percutaneous fine-needle aspiration (FNA) biopsy with concomitant core needle biopsy was performed, and a diagnosis of HRRMT was rendered. Cytologic smears were hypercellular, composed of a mixture of foamy histiocytes and a variably cohesive population of epithelioid and plasmacytoid to vaguely spindled cells in cohesive clusters and singly dispersed. Histologic material showed sheets of epithelioid and plasmacytoid to spindled cells with admixed foamy histiocytes with distended, vacuolated cytoplasm. To our knowledge, this is the first reported example of HRRMT evaluated by FNA biopsy.

Routine EWS Fusion Analysis in the Oncology Clinic to Identify Cancer-Specific Peptide Sequence Patterns That Span Breakpoints in Ewing Sarcoma and DSRCT

(1) Background: EWS fusion genes are associated with Ewing sarcoma and other Ewing family tumors including desmoplastic small round tumor, DSRCT. We utilize a clinical genomics workflow to reveal real-world frequencies of EWS fusion events, cataloging events that are similar, or divergent at the EWS breakpoint. (2) Methods: EWS fusion events from our next-generation sequencing panel (NGS) samples were first sorted by breakpoint or fusion junctions to map out the frequency of breakpoints. Fusion results were illustrated as in-frame fusion peptides involving EWS and a partner gene. (3) Results: From 2471 patient pool samples for fusion analysis at the Cleveland Clinic Molecular Pathology Laboratory, we identified 182 fusion samples evolved with the EWS gene. They are clustered in several breakpoints: chr22:29683123 (65.9%), and chr22:29688595 (2.7%). About 3/4 of Ewing sarcoma and DSRCT tumors have an identical EWS breakpoint motif at Exon 7 (SQQSSSYGQQ-) fused to a specific part of FLI1 (NPSYDSVRRG or-SSLLAYNTSS), ERG (NLPYEPPRRS), FEV (NPVGDGLFKD) or WT1 (SEKPYQCDFK). Our method also worked with Caris transcriptome data, too. Our primary clinical utility is to use this information to identify neoantigens for therapeutic purposes. (4) Conclusions and future perspectives: our method allows interpretation of what peptides result from the in-frame translation of EWS fusion junctions. These sequences, coupled with HLA-peptide binding data, are used to identify potential sequences of cancer-specific immunogenic peptides for Ewing sarcoma or DSRCT patients. This information may also be useful for immune monitoring (e.g., circulating T-cells with fusion-peptide specificity) to detect vaccine candidates, responses, or residual disease.

Superficial low-grade fibromyxoid sarcoma

BACKGROUND

Low-grade fibromyxoid sarcoma (LGFMS) typically involves deep soft tissue (beneath the fascia) of the proximal extremities and trunk. Long-term follow-up has shown a high rate of local recurrence, metastasis, and death. To the best of our knowledge, there is only one previous large series focusing on superficial LGFMS suggesting superficial tumors are disproportionately more common in children and may have a better prognosis. Our study's primary goals are to confirm these findings and increase general awareness that LGFMS may arise in superficial soft tissue.

METHODS

We retrieved our cases of superficial LGFMS diagnosed between 2008 and 2020. Available slides were reviewed, and clinical data and follow-up information were obtained.

RESULTS

The patients included nine males and 14 females with a median age of 29 years; eight (35%) were children (<18 years) and five (22%) were young adults (18-30 years). The majority involved the lower extremities (65%). The tumors were primarily centered in the subcutis (91%) and dermis (9%). Microscopically, they had typical features of LGFMS with alternating fibrous and myxoid zones composed of bland, slightly hyperchromatic spindled cells. All were positive for MUC4 by immunohistochemistry and/or FUS rearrangement by FISH. Follow-up on 14 cases ranged from 11 to 148 months (median 61 months) with no evidence of recurrences or distant metastases.

CONCLUSIONS

Compared to conventional deep-seated counterparts, superficial LGFMS is more likely to occur in the extremities of children and young adults and may have a better clinical outcome. Further studies with longer follow-up will likely help support these findings.

Nested set information derived from fusion genes in Ewing sarcoma and other cancers

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Background: Ewing family tumors including Ewing sarcoma (ES) and desmoplastic small round cell tumor (DSRCT) are characterized by EWSR1 and ETS fusion partners including EWS-FLI1, EWS-ERG, EWS-WT1, and others. Since 2019 our Next Generation Sequencing (NGS) sarcoma panel (N = 338) identified both fusion partners and exons containing the EWS breakpoint in ES and DSRCT. Hence, it should be possible to learn more about the exact breakpoints of EWS fusion genes. The molecular diversity and functionality of these fusion transcripts, especially the exact sequence, which could be identical, similar, or unique, may have significant biological implications for diagnostics and treatment options. We have used in-frame analysis of EWS gene fusion breakpoints to identify corresponding polypeptides spanning the breakpoints of the most common EWS gene fusions to provide useful insights about ES and DSRCT. Methods: Pathology reports and EWS gene fusions were analyzed using the Cleveland Clinic NGS panel which is based on anchored multiplex polymerase chain reaction (PCR) enriched for 34 gene targets. The amplicons were subjected to massively parallel sequencing with 151x2 cycle pair-end reads. An informatics pipeline was used for read alignment (GRCh37 as reference genome), fusion identification, and annotation. The DNA sequence across fusion junction and translational amino acid sequences were extracted for comparison in a preliminary teaching set (37/338 EWS fusions). Results: EWS-FLI1 fusions at exon 7-7 (chr22:29683123-chr11:128675261) and exon 7-6 (chr22:29683123-chr11:128651853) were the most common fusion genes in ES (N = 24/32;75%). Other ES gene fusions included exons 10-6, 7-10, 9-8, 7-2 EWS-FEV, 7-8 EWS-ERG, 7-9 EWS-ERG, and 10-9 EWS-ERG. EWS-WT1 gene fusions (chr22:29683123-chr11:32414301) in DSRCT exon 7-7 occurred in 4 of 5 cases (80%). In frame analysis of the common gene fusions in 75% of ES and DSRCT (total n = 37) yielded identical corresponding polypeptides that span the breakpoint (table). Conclusions: Analysis of ES and DSRCT fusion genes provides evidence that cancer-specific fusion genes are associated with common identical breakpoints and corresponding in-frame polypeptides. Our results show that the identification of in-frame polypeptides from the fusion gene sequencing can identify potential nested sets of cancer-specific mRNAs and polypeptides. This information may become relevant for diagnostic and therapeutic targets future vaccines and diagnostics against ES and DSRCT as well as other cancers characterized by fusion genes or frameshift mutations. [Table: see text]

Osteofibrous Dysplasia and Adamantinoma

For decades, the diagnosis, treatment, and even pathogenesis of the osteofibrous dysplasia/osteofibrous dysplasia-like adamantinoma/classic adamantinoma spectrum of neoplasms have been controversial. Herein, we discuss and illustrate the radiographic and histologic spectrum, differential diagnoses, unifying chromosomal and molecular abnormalities, and current controversies and treatment recommendations for each entity.

Dedifferentiated Liposarcoma: A Comprehensive Historical Review With Proposed Evidence-based Guidelines Regarding a Diagnosis in Need of Further Clarification

Among all sarcoma types, liposarcoma is the most common sarcoma that develops "dedifferentiation." Since its initial description by Dr Harry Evans, the spectrum of what is now acceptably included under the rubric of "dedifferentiated liposarcoma" (DL) has expanded, sometimes supported by cytogenetic and molecular advances. Similarly, the range of morphologic appearances considered to represent the precursor of DL, atypical lipomatous tumor (ALT)/well-differentiated liposarcoma, also has broadened, not uncommonly creating variants with significant, almost indistinguishable, morphologic overlap with occasional forms of DL, especially problematic in small biopsy specimens. More specifically, the precise criteria separating cellular forms of ALT from what some consider "low-grade" variants of DL remains controversial and inconsistently applied, even among individual pathologists within institutions. For this separation, the only objective and reproducible criteria historically shown to accurately predict a statistically significant difference in prognosis and survival is mitotic rate, alone or incorporated into a histologic grade [eg, Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC)], consistently identifying a higher grade neoplasm capable of metastases. While DL may have a better prognosis than other nonmyoid adult pleomorphic soft tissue sarcomas, definitive conclusions are difficult to establish due to nonuniform criteria for staging and establishing tumor size/volume of the high-grade component, compounded by variable definitions and thresholds for rendering the diagnosis of DL. If appropriate therapeutic approaches are to be applied to DL, there needs to uniform agreement regarding the histologic definition, grading, and staging of DL. Herein, is a comprehensive historical perspective on DL and ALT/well-differentiated liposarcoma, seeking to provide insights, updates, and a proposal for uniform, evidence-based guidelines.

Ossifying pyogenic granuloma: A rare variant usually not recognized

Pyogenic granuloma (PG) represents a polypoid and lobular, capillary lesion, resembling granulation tissue, usually occurring on skin or mucosal surfaces. The occurrence of metaplastic ossification is extremely rare in PG. We present three cases of PG with metaplastic ossification. All three patients were men, aged 18-66 years. In all cases, the lesions occurred on the digits, particularly in or around the nail bed. Histopathologically, these superficial dermal-based tumors were characterized by classic features of PG, namely circumscribed, exophytic to polypoid proliferations of capillary-sized blood vessels in a lobular arrangement. The characteristic vascular component also was intimately associated with spicules and trabeculae of metaplastic bone formation rimmed by osteoblasts and osteoclasts. This osseous component was diffusely distributed in two cases and more localized in another. We speculate that ossification in PGs possibly represents a reactive process in response to chronic injury. We believe that ossifying PG is likely under-recognized and often mistaken for other entities also arising in the extremities and characterized by osseous metaplasia.

Accurate and Reliable Diagnosis of Avascular Necrosis of the Femoral Head From Total Hip Arthroplasty Specimens Requires Pathologic Examination

OBJECTIVES

To evaluate the necessity of pathologic examination for confirming the diagnosis of avascular necrosis (AVN).

METHODS

We retrospectively reviewed consecutive nonfractured total hip arthroplasty cases (n = 1,722), comparing operative diagnoses and radiologic data with final histologic diagnoses, focusing specifically on AVN.

RESULTS

Among 199 histologically confirmed cases of AVN, 62 (31%) had a preoperative diagnosis of osteoarthritis/degenerative joint disease (OA/DJD); 58 of the latter patients had radiology reports, but only two (3%) documented AVN. Patients with AVN preoperatively diagnosed as OA/DJD were significantly older (mean, 65 years) than patients with AVN correctly diagnosed clinically (mean, 52 years; P < .00001). Among 163 cases with a preoperative diagnosis of AVN, 26 (16%) were confirmed as OA/DJD; the radiology report incorrectly diagnosed AVN in 17 (65%) patients. These latter patients also were significantly older (mean, 60 years) than patients with AVN correctly diagnosed clinically (P = .0008). Patients with a preoperative clinical and/or radiologic diagnosis of AVN were more likely to be younger and have known AVN risk factors.

CONCLUSIONS

Accurate and reliable diagnosis of AVN requires pathologic examination, especially among older patients without known risk factors. Prompt diagnosis may lead to behavioral changes in affected patients that reduce the risk of subsequent lesions.

The Incidence and Significance of Calcium Pyrophosphate Dihydrate Deposits in Histologic Examinations of Total Hip, Knee, and Shoulder Joint Arthroplasties

CONTEXT.—

The incidence, distribution, and significance of calcium pyrophosphate dihydrate deposition (CPPD) disease have not been extensively compared among various total joint resections.

OBJECTIVE.—

To investigate and define the clinical and pathologic features of CPPD in hip, shoulder, and knee arthroplasties.

DESIGN.—

We retrospectively reviewed consecutive total hip, knee, and shoulder arthroplasty cases (N = 3195) confirmed pathologically between January 1, 2017, and October 10, 2018, comparing clinical and pathologic data.

RESULTS.—

Among 2004 hip arthroplasties, 61 (3%) had CPPD on pathologic examination; the majority had a histologic diagnosis of osteoarthritis followed by fracture and avascular necrosis. Of 1113 knee arthroplasties, 98 (9%) had CPPD; all had a histologic diagnosis of osteoarthritis. Among 78 shoulder arthroplasties, 10 (13%) had CPPD; all but one had a histologic diagnosis of osteoarthritis. Patients with hip and knee CPPD were significantly older than those without CPPD. Of the 169 pathologically detected CPPD cases, only 35 (21%) were documented on preoperative radiologic images or by other clinical means; radiology reports were significantly more likely to document chondrocalcinosis in the knees than in the hips. Histologically, CPPD were noted almost exclusively in the separately submitted soft tissues/joint capsule, concomitantly involving the articular cartilage surface in only 3.0% (5 of 169) of cases.

CONCLUSIONS.—

Calcium pyrophosphate dihydrate deposition is more than twice as likely to occur in the knees and shoulders compared with the hips. Patients with CPPD in the knees or hips are usually not recognized preoperatively/radiologically and constitute a significantly older population. Reliably establishing the diagnosis of CPPD requires pathologic examination of the submitted soft tissue/joint capsule.

Gorham-Stout disease of the spine presenting with intracranial hypotension and cerebrospinal fluid leak: A case report and review of the literature

Background:

Gorham-Stout (GS) disease or “vanishing bone disease” is rare and characterized by progressive, spontaneous osteolysis resulting in loss of bone on imaging studies. Treatment modalities include combinations of medical and/or surgical treatment and radiation therapy.

Case Description:

A 14-year-old female with GS disease presented with a 1-year history of thoracic back pain and atypical headaches consistent with intracranial hypotension. Magnetic resonance imaging and operative findings demonstrated a spontaneous thoracic cerebrospinal fluid leak (CSF) (e.g., that extended into the pleural cavity) and complete osteolysis of the T9-10 posterior bony elements (e.g., including the rib head, lamina, and transverse processes). The patient underwent repair of CSF fistula followed by a T6-11 instrumented fusion.

Conclusion:

This case of GS disease, involving a thoracic CSF fistula and absence/osteolysis of the T9-T10 bony elements, could be successfully managed with direct dural repair and an instrumented T6-T11 fusion.

Diagnostic Utility of a Custom 34-Gene Anchored Multiplex PCR-Based Next-Generation Sequencing Fusion Panel for the Diagnosis of Bone and Soft Tissue Neoplasms With Identification of Novel USP6 Fusion Partners in Aneurysmal Bone Cysts

CONTEXT.—

Bone and soft tissue tumors are heterogeneous, diagnostically challenging, and often defined by gene fusions.

OBJECTIVE.—

To present our experience using a custom 34-gene targeted sequencing fusion panel.

DESIGN.—

Total nucleic acid extracted from formalin-fixed, paraffin-embedded (FFPE) tumor specimens was subjected to open-ended, nested anchored multiplex polymerase chain reaction and enrichment of 34 gene targets, thus enabling detection of known and novel fusion partners.

RESULTS.—

During a 12-month period, 147 patients were tested as part of routine clinical care. Tumor percentage ranged from 10% to 100% and turnaround time ranged from 3 to 15 (median, 7.9) days. The most common diagnostic groups were small round blue cell tumors, tumors of uncertain differentiation, fibroblastic/myofibroblastic tumors, and adipocytic tumors. In-frame fusion transcripts were identified in 64 of 142 cases sequenced (45%): in 62 cases, the detection of a disease-defining fusion confirmed the morphologic impression; in 2 cases, a germline TFG-GPR128 polymorphic fusion variant was detected. Several genes in the panel partnered with multiple fusion partners specific for different diagnoses, for example, EWSR1, NR4A3, FUS, NCOA2, and TFE3. Interesting examples are presented to highlight how fusion detection or lack thereof was instrumental in establishing accurate diagnoses. Novel fusion partners were detected for 2 cases of solid aneurysmal bone cysts (PTBP1-USP6, SLC38A2-USP6).

CONCLUSIONS.—

Multiplex detection of fusions in total nucleic acid purified from FFPE specimens facilitates diagnosis of bone and soft tissue tumors. This technology is particularly useful for morphologically challenging entities and in the absence of prior knowledge of fusion partners, and has the potential to discover novel fusion partners.

Sclerosing epithelioid fibrosarcoma of bone: morphological, immunophenotypical, and molecular findings of 9 cases

Primary sclerosing epithelioid fibrosarcoma (SEF) of bone is a rare and scarcely reported neoplasm. We document clinicopathological and molecular features of 9 additional cases. Five males and 4 females had a mean age of 39 years (14-71 years). Most tumors affected flat/irregular bones; only 3 cases involved a long bone. By radiology, it has characteristic radiographic features of a predominantly lytic expansile lesion with a sclerotic rim. Referring diagnoses were SEF (n = 2), low-grade osteosarcoma (n = 2), chondrosarcoma (n = 1), and chondromyxoid fibroma (n = 1). Histologically, five cases revealed classical morphology of SEF of soft tissue. Remaining cases were classified as hybrid SEF/low-grade fibromyxoid sarcoma, characterized by spindle or stellate cells, prominent stroma, and giant hyalinized areas. Various morphological deviations such as prominent vasculature (n = 3), osteoid-like material (n = 4), or parallel bone trabeculae (n = 2) were observed. Immunohistochemically, all cases showed diffuse and strong MUC4 expression. SATB2 was observed in 5/8 cases. Using FISH, EWSR1, and FUS rearrangements were detected in 4 cases and 1 case, respectively. EWSR1-CREB3L1 fusion was identified in 1 additional case by next-generation sequencing. Recurrence and metastasis were observed in 1 case and 2 cases, respectively. All but one patient were alive with disease for a mean interval of 31 months. SEF of bone is a relatively indolent sarcoma of adults, most commonly located in the flat/irregular bones. Due to overlapping histological features, it is often misdiagnosed as osteosarcoma or a chondroid tumor. Most SEF of bone exhibit EWSR1 rearrangements, but rare cases may harbor a FUS gene fusion.

Revision Total Wrist Arthroplasty Due to Polyethylene Wear, Metallosis-Induced Carpal Tunnel Syndrome, Distal Ulnar Impingement, and Fourth Carpometacarpal Joint Pain: Case Report and Pitfalls to Avoid

Background: Total wrist arthroplasty (TWA) is indicated to alleviate pain secondary to arthritis while preserving wrist motion. Despite vigilant measures, TWAs are susceptible to complications. The current case illustrates an array of preventable complications which are addressed through operative technique in a revision setting. Case presentation: The patient was a 72-year-old man who presented with chronic pain at the fourth carpometacarpal joint (CMCJ) and distal radioulnar joint with paresthesias in the median nerve distribution. Surgery was undertaken to address the following complications secondary to a previous TWA: impingement of the native distal ulna on the prosthesis, carpal tunnel due to metallosis and polyethylene synovitis, loose carpal component, and prominent screw at the fourth CMCJ. Surgical correction included open carpal tunnel release with extensive flexor tenosynovectomy, distal ulna resection and implant arthroplasty with shortening, revision of carpal component with bone grafting, and shortening of the ulnar screw to avoid crossing the fourth CMCJ. Within 6 months of the procedure, the patient reported resolution of neuropathic symptoms and pain-free motion of the wrist. Discussion: Preventable complications associated with TWA are individually highlighted. In addition, we compare and contrast our approach and surgical technique to current reported literature. Overall, we provide education and guidance to avoid possible TWA pitfalls. Conclusion: With this case report, we hope to increase TWA knowledge with emphasis on the requirements of judicious patient selection, preoperative planning, meticulous surgical technique, and complication awareness for subsequent optimization of wrist function, stability, and durability.

Upper extremity myxofibrosarcoma mimicking an erosive inflammatory arthritis: a case report

Myxofibrosarcoma is a malignant fibroblastic soft tissue neoplasm containing a variable amount of myxoid stroma that commonly presents as a slow-growing mass in elderly patients. The neoplasm may be superficial or deep to the muscle fascia and characteristically has an infiltrative growth pattern with a dominant or multinodular mass. We describe an unusual case of high-grade myxofibrosarcoma of the wrist and forearm that infiltrated the muscles, tendons, and wrist joint, causing bone erosions. The tumor was mistakenly diagnosed as synovitis and a chronic, erosive, inflammatory process. The diffuse nature, absence of a dominant mass, and radiographic appearance complicated the diagnosis. Although neoplasms of the synovial spaces are rare, this case demonstrates that tumors with a highly infiltrative growth pattern can mimic inflammatory synovitis and that neoplasms should be considered in the differential diagnosis when clinical and laboratory features are discordant with the imaging appearance.

Multiloculated mesothelial cyst presenting as a malignant mimic

A 46-year-old woman was referred for a second opinion regarding an intra-abdominal mass discovered on imaging performed for abdominal pain and distension. The tumour appeared to involve the small bowel, left colon and mesentery and was initially thought to be consistent with an infiltrative tumour or loculated mucinous ascites. Due to the unusual appearance of the tumour and suspicion for an omental-based mass, a laparoscopic resection was recommended to the patient. Intraoperatively, the tumour was found to be a multiloculated, benign appearing, omental cyst without involvement of the bowel and was completely resected laparoscopically. Pathology demonstrated a multiloculated peritoneal mesothelial cyst.

Fine needle aspiration biopsy diagnosis of primary clear cell chondrosarcoma: A case report

Clear cell chondrosarcoma is a rare chondrosarcoma variant often involving the long bone epiphyses of young to middle aged adults. We report herein a case involving the left femoral head in a 25-year-old female with a 3-month history of worsening left hip pain. Radiographs revealed a complex, multifocal and lytic lesion centered in the left proximal femoral epiphysis with involvement of the femoral neck. Computed tomography-guided fine needle aspiration biopsy with concomitant core needle biopsy was performed, and a diagnosis of clear cell chondrosarcoma was rendered. Cytologic smears revealed aggregates of matrix material accompanied by a population of mostly uniform spindled to epithelioid and histiocytoid cells, rarely accompanied by osteoclast-type giant cells. The patient underwent surgical resection with -total hip replacement, and subsequent pathologic examination confirmed the initial needle biopsy diagnosis. There has been no evidence of local recurrence or distant metastases with 3-years follow-up. To our knowledge, this is the first reported example of a primary clear cell chondrosarcoma initially evaluated by fine needle aspiration biopsy.

Identifying BRAF mutations in colorectal cancer (CRC) by initial immunohistochemical (IHC) staining for mismatched protein expression as part of a Lynch syndrome screening program: A distinct clinicopathologic entity

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Background: Multiple genetic mutations resulting in different clinical phenotypes have been found in colorectal adenocarcinoma. Mutation in the BRAF oncogene is a key step in malignant transformation within the methylator pathway leading to colorectal cancer. There is little data regarding the identification of the subset of CRCs exhibiting mutations in the BRAF oncogene with initial IHC staining, as well as a paucity of information describing this unique subset of colorectal cancers Methods: Between 1/1/11 to 12/31/12, all newly diagnosed CRCs underwent IHC testing for MLH1, MSH2, MHS6, and PMS2 protein expression if sufficient pathologic material existed. If MLH1 protein expression was absent, BRAF V600E mutation analysis was preformed. Patient demographics, pathology and outcomes were examined through chart review. Statistical associations were determined by the TTest, Fisher’s exact probability test and Cox regression analysis of Kaplan-Meier curves. Results: 314 newly diagnosed CRC patients were identified and 278 (89%) underwent IHC staining (study population). 48 had absent MLH1 protein expression (15%) and underwent BRAF mutational analysis. 35/48 had the V600E mutation. Comparing the BRAF mutated group to the study population without BRAF mutation showed statistically significant differences. These differences included median age at diagnosis (78 vs. 65 years, p < 0.0001), female sex (77% vs. 51%, p = 0.0037), right colon location (77% vs. 42%, p = 0.0001) and significant mucinous component denoted pathologically (31% vs. 7%, p = 0.0001). There was no difference in stage of CRC at diagnosis between the groups. Survival rates at one year based on Kaplan Meier curves were 65% vs. 82% and results will be updated. Conclusions: BRAF mutations in CRC are associated with unique clinicopathologic characteristics and overall worse prognosis. This subgroup of CRC can be identified as part of a Lynch Screening program via ICH staining of the mismatch repair proteins MLH1, MSH2, MSH6, and PMS2.

Chondrosarcoma Variants

This article presents a review of chondrosarcoma variants, with a focus on the extraordinarily rare variants of chondrosarcoma in which hyaline cartilage is not the dominant feature. Discussed are the differential diagnoses for these neoplasms, radiologic studies, gross and microscopic features, and prognosis. Summaries are provided of the key features for the major variants.

Deep juvenile xanthogranuloma presenting as a chest wall mass: a case report

BACKGROUND

Juvenile xanthogranulotna (JXG) is a non-Langerhans cell histocytic proliferation that may appear as an extracutaneous deep-seated lesion and give a broad clinical dijffrrential diagnosis. We report the fine needle aspiration cytologv (FNAC) findings of deep JXG.

CASE

A 5-month-old African-American boy was incidentally found to have a chest wall mass on a chest radiograph obtained for an unrelated medical problem. Subsequent computed tomographic scans documented a 3.8-cm soft tissue mass that involved the right chest wall centered around the fifth rib. A broad clinical differential diagnosis prompted FNA to evaluate the lesion. Aspirate smears of the mass exhibited numerous finely vacuolated histocytes, eosinophils, multinucleated giant cells and scattered Touton giant cells. Many of the histiocytes had reniform or grooved nuclei, resembling Langerhans cells. The histiocytes were immunoreactive for CD68 but were nonreactive for CD1a and S-100 protein. Subsequent excisional biopsy confirmed the diagnosis of JXG. In addition, the tumor was strongly immunoreactive for factor XIIIa.

CONCLUSION

JXG should be considered in the diferential diagnosis of any histocytic/fibrohistiocytic soft tissue lesion of childhood, and this entity can be accurately diagnosed by FNAC and immunohistochemical findings.

The usefulness of cytogenetic analysis in fine needle aspirates for the histologic subtyping of sarcomas

Conventional cytogenetic analysis performed from open biopsy tissue samples may be a useful adjunct for the histologic subtyping of bone and soft tissue sarcomas. However, its diagnostic utility in fine needle aspiration biopsy (FNAB) specimens is unclear. We retrospectively reviewed 24 consecutive FNAB bone and soft tissue sarcoma specimens, procured from 1995 to 2003, in which aspirated material was obtained for cytogenetic analysis. The study sample included eight Ewing sarcomas, six synovial sarcomas, five rhabdomyosarcomas, two myxoid liposarcomas, and one each of myxoid chondrosarcoma, osteosarcoma, and atypical lipoma. Cytogenetic analysis confirmed the t(X;18) in all six synovial sarcomas and the t(11;22) in three Ewing sarcomas. The t(2;13) was strongly suggested in one alveolar rhabdomyosarcoma. For two of these cases (both of which were synovial sarcomas), cytogenetic analysis was necessary for definitive diagnosis. While the positive cytogenetic results were supportive in the remainder, all were initially and accurately subtyped based on cytomorphology and/or immunohistochemistry. Cytogenetic analysis was noncontributory (eg no growth) in 14 sarcoma cases, but excluding the case of atypical lipoma, this did not preclude the rendering of an accurate diagnosis. Cytogenetic analysis can be performed on FNAB specimens from bone and soft tissue sarcomas and may be a useful diagnostic aid in difficult cases. However, when cell block material is available for immunohistochemistry, the majority of such cases are successfully subtyped.

Diagnostic pitfalls associated with fine-needle aspiration biopsy in a patient with the myxoid variant of monophasic fibrous synovial sarcoma

Synovial sarcoma (SS) is one of the most common soft tissue tumors that typically presents in the extremities of young adults, but may occur at any site and affect children during the first decade. Herein we discuss a 12-yr-old male who complained of left foot pain and plantar mass. A fine-needle aspiration biopsy of an 8 cm subcutaneous mass was performed revealing a myxoid spindle cell neoplasm. The cytologic differential diagnosis included a myxoid neurofibroma, neurothekeoma, and a myxoid sarcoma. Subsequent excision of the mass revealed a monophasic fibrous SS with myxoid features. Examination of the tissue by fluorescence in situ hybridization confirmed the presence of characteristic SS SYT gene rearrangement at chromosome 18q11.2. This case underscores that the cytologic distinction of mxyoid spindle cell tumors may be challenging. We report the cytologic features of a myxoid monophasic fibrous SS, and discuss its distinction from other benign and malignant myxoid soft tissue neoplasms.

Potential sampling error in fine needle aspiration biopsy of dedifferentiated chondrosarcoma: a report of 4 cases

BACKGROUND

Dedifferentiated chondrosarcoma is a rare, poorly understood and often fatal sarcoma that usually manifests as a high grade, non-cartilage-producing sarcoma juxtaposed against a low grade chondrosarcoma. A correct diagnosis requires recognition of both components. In the absence of complete resection, rendering a specific diagnosis on small biopsy specimens, such as fine needle aspiration biopsy (FNAB), may be extraordinarily difficult.

CASES

We retrospectively reviewed 4 cytology samples (3 primary, 1 metastatic) from 3 patients with dedifferentiated chondrosarcoma, initially analyzed by FNAB, emphasizing the potential for sampling error. Two women, aged 78 and 57 years, both of whom had prior histories of carcinoma, presented with lesions involving the right and left femur, respectively. One 27-year-old man with multiple osteochondromatosis developed a dedifferentiated chondrosarcoma of the left pelvis. Two primary cytologic specimens consisted of moderately cellular smears containing a spindled to polygonal, nonspecific, pleomorphic sarcoma unaccompanied by definite matrix material; 1 of these had a concomitant core needle biopsy (CNB), also demonstrating pleomorphic sarcoma. The third primary cytologic specimen revealed low grade chondrosarcoma, but a concomitant CNB showed only a high grade, non-matrix-producing sarcoma. The last patient developed a metastasis to the opposite femur; FNAB revealed a high grade spindle cell sarcoma. In none of the FNAB or CNB specimens were both low and high grade components of dedifferentiated chondrosarcoma recognized. However, the diagnosis was strongly suspected based on the clinical and radiographic findings.

CONCLUSION

Due to sampling error, the diagnosis of dedifferentiated chondrosarcoma may be difficult to establish by cytologic examination alone. Clinical and radiographic correlation is essential for an accurate diagnosis.

Recommendations for the reporting of bone tumors

The diagnosis of a bone tumor is often an arduous task, even for the most experienced orthopedic pathologist. As a starting point, the classification of bone tumors is based on a histogenetic perspective encompassing the type of matrix produced (or not produced) by the tumor. In general, the surgical pathology report should include data pertinent to the treatment and prognostication of an individual patient, and the report should be delivered to the clinician in a clear, concise fashion. Reporting of most bone tumors is similar and includes such information as the type of surgery done, anatomic site, histological type and grade of the tumor (if applicable), and the adequacy of surgical margins. Special emphasis is needed for those tumors with distinct and well-established prognostic and therapeutic features such as osteosarcoma and Ewing's sarcoma/peripheral neuroectodermal tumor. Our recommendation emphasizes a standardized protocol for these sarcomas, especially in light of evidence that postchemotherapeutic tumor necrosis is of prognostic significance. It is also important to note that radiographic imaging plays a very important, often critical, role in allowing the pathologist the opportunity to reach the best final diagnosis. This is especially true when a malignant interpretation is contemplated and in subtyping lesions. We recommend close collaboration between musculoskeletal radiologists, clinicians, and pathologists when dealing with complicated neoplasms of bone.

Fine needle aspiration biopsy of soft tissue sarcomas: utility and diagnostic challenges

The role of fine needle aspiration biopsy (FNAB) as the primary modality for the initial diagnosis of previously undiagnosed soft tissue sarcomas presents several important challenges. Most practicing pathologists are inexperienced with the wide array of soft tissue neoplasms and their morphologic heterogeneity, making them susceptible to misdiagnosis. However, in the hands of experienced cytopathologists, FNAB in conjunction with ancillary techniques has a diagnostic accuracy approaching 95% for the diagnosis of malignancy. FNAB has been shown to have a diagnostic yield nearly identical with core needle biopsy while avoiding significant clinical complications. Nevertheless, FNAB has certain limitations related to the accurate histologic grading and subtyping of certain subgroups of sarcomas. It may also be difficult to accurately distinguish between low-grade sarcomas and benign or borderline cellular lesions, especially in the spindle cell sarcoma subgroup. The aim of this review is to highlight the utility and limitations of FNAB in the primary diagnosis of soft tissue sarcomas, highlight diagnostically challenging lesions, and comment on the limitations of FNAB in providing a "definitive" diagnosis.

Inflammatory myofibroblastic tumor with bone marrow involvement. A case report and review of the literature

Inflammatory myofibroblastic tumor, also referred to as inflammatory fibrosarcoma, is a rare tumor composed of myofibroblastic spindle cells of uncertain etiology and disputed nosology. We report a case of inflammatory myofibroblastic tumor of the omentum with involvement of the bone marrow in an 18-year-old man. Histologic and immunohistochemical studies of the abdominal mass and bone marrow were consistent with inflammatory myofibroblastic tumor. Additionally, fluorescence in situ hybridization using a probe specific for the ALK gene showed disruption of the gene. The literature is reviewed with emphasis on the ability of inflammatory myofibroblastic tumor to recur, metastasize, and cause mortality.

Clinicopathologic analysis of HER-2/neu immunoexpression among various histologic subtypes and grades of osteosarcoma

Overexpression of the HER-2/neu oncogene appears to have prognostic significance in breast cancer. Recently, some have reported a relationship between increased immunohistochemical expression in osteosarcoma and poor clinical outcome. Despite limited data, a pilot trial of Herceptin, which targets the oncogene product, has been initiated for the therapy of some metastatic osteosarcomas (CCG-P9852). Archival formalin-fixed, paraffin-embedded tissue obtained from 41 patients diagnosed with osteosarcoma was examined immunohistochemically by 2 antibodies against the HER-2/neu oncogene product: CB-11 (monoclonal, 1/100) and Oncor (polyclonal, 1/200). All but one tumor (case of recurrent dedifferentiated parosteal osteosarcoma) represented primary tumor samples; when applicable, only prechemotherapy biopsies were analyzed. The study sample included the full spectrum of histologic subtypes and grades of osteosarcoma (25 conventional high grade; 3 telangiectatic; 1 small cell; 6 parosteal; 1 periosteal; and 5 low-grade intramedullary). A case of metastatic breast cancer with known overexpression of the HER-2/neu oncogene served as the positive control. Complete membranous positivity, considered prognostically significant in breast cancer, was not seen in any of our osteosarcoma cases. At least focal cytoplasmic positivity was documented in 40 (98%) tumors using the CB11 antibody and in 34 (83%) using the Oncor antibody. The intensity of the cytoplasmic staining (0, 1-3+) did not correlate with histologic subtype/grade, response to chemotherapy (<90% versus > or = 90% necrosis), metastasis, or survival. Immunohistochemical overexpression of the HER-2/neu oncogene, defined as complete membranous positivity, is not present in our series of osteosarcomas. Cytoplasmic positivity is observed in most osteosarcomas, irrespective of histologic subtype/grade, and is not associated with response to preoperative chemotherapy or disease progression.

Prostate carcinoma metastatic to the cervical lymph nodes: report of two cases and review of the literature

The cervical lymph nodes are a common site of metastasis for cancers originating in the upper aerodigestive tract. Rarely, cancers originating from sites other than the head and neck can metastasize to the cervical lymph node chain. We report on 2 recent patients with metastatic prostate cancer to the cervical lymph nodes.

The role of fine needle aspiration biopsy in the diagnosis and management of osteosarcoma

We retrospectively reviewed our experience with fine needle aspiration biopsy (FNAB) in the diagnosis and management of skeletal osteosarcoma. The bi-institutional study sample involved 30 consecutive aspirates from 29 patients (28 primary tumors, 1 pulmonary metastasis, 1 local recurrence). There were 17 children and 12 adults. Two aspirates were unsatisfactory for diagnosis. Of the adequate primary osteosarcoma cases analyzed by FNAB, 24 of 26 were diagnosed as osteosarcoma. All pediatric cases were correctly interpreted as osteosarcoma and treated appropriately. There were 2 incomplete diagnoses. A secondary osteosarcoma arising within an otherwise clinically, radiologically, and histologically typical giant cell tumor (malignant giant cell tumor) was not diagnosed preoperatively on FNAB due to nonrepresentative sampling. Chronologically, the first patient with osteosarcoma analyzed by FNAB was diagnosed simply as "spindle cell neoplasm." No complications resulted from the procedure. With adequate clinical and radiologic correlation, FNAB represents a technically, easily performed, cost-effective, and accurate procedure for establishing the diagnosis of skeletal osteosarcoma. Immediate interpretation of aspirated material allows for therapy planning and oncologic consultation at the initial clinic visit.

Fine-needle aspiration biopsy of sarcomas and related tumors

BACKGROUND

Largely due to a lack of experience, familiarity, and/or confidence, few centers rely on simple fine-needle aspiration biopsy (FNAB) for the diagnosis of sarcomas and related tumors.

METHODS

The authors have reviewed their own experience in more than 200 cases of FNAB of bone and soft-tissue tumors, as well as cases reported in the literature.

RESULTS

FNAB has proven to be accurate and useful in 8 consecutive years of clinical experience. No serious complications have occurred.

CONCLUSIONS

FNAB is recommended as an integral part of the initial evaluation of amenable orthopaedic tumors, including sarcomas, especially in cases with classic clinical and radiographic findings.

Is fine-needle aspiration biopsy a practical alternative to open biopsy for the primary diagnosis of sarcoma? Experience with 140 patients

We reviewed the clinicopathologic features of 145 consecutive fine-needle aspiration biopsy (FNAB) specimens from 140 patients without a previous diagnosis of sarcoma. Among 138 adequate specimens, 42 bone sarcomas and 80 soft tissue sarcomas were recognized as sarcomas; histologic subtyping was easier in bone than in soft tissue sarcomas and in pediatric than in adult cases. There was no correlation in accuracy of subtyping in low- vs high-grade sarcomas. FNAB was most accurate for subtyping of skeletal osteosarcoma, pediatric small round cell bone/soft tissue sarcomas, synovial sarcoma, skeletal chondrosarcoma, and adult myxoid soft tissue sarcomas. Although almost always recognized as sarcoma, subtyping of adult pleomorphic soft tissue sarcomas generally was not possible but did not influence therapy; all were considered high-grade sarcomas for treatment purposes. There were 4 misinterpretations of subtype in soft tissue sarcomas; none resulted in a change in therapy. Cytogenetic analysis on aspirated material confirmed t(11;22) in 2 Ewing and t(X;18) in 3 synovial sarcomas. No procedure-related complications occurred. Among bone and soft tissue sarcomas, FNAB was sufficient for initiation of definitive therapy in 87% and 83% of patients, respectively. Most FNAB specimens from bone and soft tissue sarcomas are recognized easily as sarcoma, but subtyping seems more accurate in bone sarcomas. Although histologic subtyping of adult soft tissue sarcomas is often impossible, no influence on initial therapy is usually observed. In contrast, subtyping of pediatric sarcomas by FNAB seems highly accurate and is necessary for appropriate therapy.

Pathology of skeletal metastases

Metastatic disease involving the skeleton is an unfortunate and common occurrence in cancer patients. Choosing the best diagnostic approach requires knowledge of the patient's clinical history, the radiologic appearance of the lesion, the differential diagnosis, and the ability of the diagnostic modality to answer the questions that must be addressed. In difficult cases, interaction between the pathologist and clinician before biopsy may make the difference between a rapid procedure serving to definitively diagnose and effectively stage a patient and a costly procedure that provides little or no information.

The value of fine-needle aspiration biopsy in the differential diagnosis of adult myxoid sarcoma

BACKGROUND

The usefulness of fine-needle aspiration biopsy (FNAB) for the histologic subtyping of specific sarcomas still is somewhat controversial but is becoming increasingly popular in the U.S.

METHODS

To determine the accuracy and usefulness of FNAB in the differential diagnosis of myxoid sarcoma, the authors retrospectively reviewed 18 FNAB specimens (16 primary tumors, 1 local recurrence, and 1 metastasis) in 18 patients. The study sample included myxoid/round cell liposarcoma in six patients, myxofibrosarcoma in six patients, myxoid chondrosarcoma in five patients, and myxoid leiomyosarcoma in one patient.

RESULTS

All but one tumor were recognized correctly as malignant. With regard to primary tumors, a specific cytologic diagnosis was rendered in 13 of 16 patients (81%). Problematic areas included the diagnosis of high grade myxofibrosarcoma with minimal amounts of myxoid stroma, myxoid liposarcoma with a predominant round cell component, and the single case of myxoid leiomyosarcoma.

CONCLUSIONS

FNAB represents a valuable diagnostic tool for the differential diagnosis of myxoid sarcoma, especially myxofibrosarcoma, low grade myxoid liposarcoma, and myxoid chondrosarcoma. Due to its prognostic and therapeutic significance, the presence of a predominant round cell component in myxoid liposarcoma should be documented adequately. Other sarcomas (e.g., leiomyosarcoma) rarely may exhibit a prominent myxoid stroma and therefore should be considered in the differential diagnosis of adult myxoid sarcoma.

Fibrocartilaginous mesenchymoma of bone: case report and review of the literature

Fibrocartilaginous mesenchymoma of bone is a rare primary neoplasm. Our literature search produced only 12 previously reported cases. Radiographic and computed tomography (CT) findings have been described, but the magnetic resonance imaging (MRI) appearance has not been reported previously. We report a patient with fibrocartilaginous mesenchymoma of the ilium and describe the imaging findings on conventional radiography, bone scan, CT, and MRI.

Fine-needle aspiration biopsy of soft tissue sarcomas. A cytomorphologic analysis with emphasis on histologic subtyping, grading, and therapeutic significance

Because therapy for sarcoma often incorporates histologic subtype, grade, stage, and anatomic location, establishing a specific histologic subtype often is essential. To evaluate the effectiveness of fine-needle aspiration biopsy (FNAB) in histologic subtyping of soft tissue sarcomas, we retrospectively reviewed 73 consecutive aspirates from 67 patients, none of whom had a previously established sarcoma diagnosis. Sarcoma cases were subgrouped according to predominant cytomorphologic features: pleomorphic cell, 19; small round cell, 18; spindle cell, 18; myxoid, 10; epithelioid/polygonal cell, 7; 1 case of well-differentiated liposarcoma was analyzed separately. Ancillary studies were used for 25 cases. Among adequate specimens, 61 tumors were recognized as sarcoma. A specific and accurate histologic subtype was determined in 34 cases. Ancillary studies were most useful for histologic subtyping of small round cell and spindle cell sarcomas. Myxoid sarcomas were subtyped easily based solely on histomorphologic features. Pleomorphic cell and epithelioid/polygonal cell sarcomas were recognized easily as malignant but difficult to subtype by FNAB. With the exception of small round cell sarcomas, histologic subtyping of a sarcoma usually did not directly influence therapy. With meticulous attention to clinicopathologic features and ancillary techniques, many sarcomas, especially small round cell, spindle cell, and myxoid types, may be subtyped successfully by FNAB, within limitations.

Histologic prognostication in soft tissue sarcomas: grading versus subtyping or both? A comprehensive review of the literature with proposed practical guidelines

Despite the validation of many histologic grading systems for soft tissue sarcomas, none have been universally accepted. Because of the overall rarity of specific histologic sarcoma subtypes, evaluation of grading systems and their prognostic significance have tended to base the results on sarcomas as a general group, diminishing the value and significance of histologic subtyping. A representative review of the literature regarding histologic grading of soft tissue sarcomas and its relationship to histologic subtype, stage, and prognosis is analyzed and discussed. Histologic grading of many soft tissue sarcomas appears to be a valuable predictor of patient survival, as confirmed by the literature. However, accurate histologic subtyping is essential for accurate histologic grading. Histologic grading in some sarcoma subtypes is probably not applicable and may underestimate biologic behavior. Clinicians and pathologists should be aware of the limitations, prognostic significances, and relationships of histologic subtyping and histologic grading in the therapeutic management and prognostication of soft tissue sarcomas.

Myxofibrosarcoma of soft tissues: cytomorphologic analysis of a series

Within the English literature, myxofibrosarcoma is a recently described entity. Although the histopathologic features have been reported, the cytomorphologic spectrum of myxofibrosarcoma has been far less documented. The cytologic findings of six fine-needle aspiration biopsy specimens (five primaries, one local recurrence) from six patients are described. The patients' ages ranged from 26-77 yr; there were four women and two men. The aspiration biopsy specimens ranged from slightly to markedly cellular. Although a myxoid granular to filamentous background was observed at least focally in all cases, the volume of the myxoid material was inversely proportional to the cellularity and grade of the tumor. Individual tumor cells were round to spindled, often displaying a wide range of cell shapes and sizes. Nuclei were generally large, pleomorphic, and hyperchromatic, frequently containing prominent nucleoli. Cytoplasm ranged from scant to dense and tapering. Multinucleated tumor giant cells were occasionally observed. In general, low- and intermediate-grade myxofibrosarcomas were more easily recognized in cytologic preparations. In contrast, high-grade myxofibrosarcoma was more difficult to specifically subtype and not easily distinguished from other adult pleomorphic sarcomas.

The role of fine-needle aspiration biopsy in the initial diagnosis of pediatric bone and soft tissue tumors: an institutional experience

The use of fine-needle aspiration biopsy (FNAB) in the initial evaluation of pediatric bone and soft tissue tumors is controversial, especially for those patients being considered for histiogenetic-specific therapeutic protocols, e.g., the Intergroup Rhabdomyosarcoma Study Group, the Pediatric Oncology Group. We retrospectively reviewed 33 consecutive FNAB specimens (28 primary tumors, 5 metastases) from 32 pediatric patients (< or = 19 yr of age), none of whom had a previously established tumor diagnosis. In one patient, FNAB of the primary tumor and a presumed axillary metastasis were obtained concomitantly. The cytomorphologic analysis included osteosarcoma, eight patients; rhabdomyosarcoma, five; neuroblastoma, five; Ewing's sarcoma/primitive neuroectodermal tumor, four; Langerhans' cell histiocytosis, three; and one each synovial sarcoma, undifferentiated sarcoma, infantile myofibromatosis, fibroma, chondroblastoma, chondromyxoid fibroma, and desmoplastic small round-cell tumor. Ancillary studies, e.g., immunocytochemical analysis, were used in 13 cases. Cytogenetic analysis helped to confirm one Ewing's sarcoma [t (11;22) (q24;q12)] and one synovial sarcoma [t(X;18) (p11;q11)]. With adequate FNAB specimens, a histogenetic-specific diagnosis was rendered in 27 (93%) of 29 cases, and all were correctly recognized as either benign or malignant. One case each of Langerhans' cell histiocytosis, chondroblastoma, and infantile myofibromatosis yielded unsatisfactory specimens. Fibroma and desmoplastic small round-cell tumor were initially misclassified as nodular fasciitis and rhabdomyosarcoma, respectively. Of 18 patients clinically eligible for histogenetic-specific therapy protocols, an accurate diagnosis was obtained in 17 patients. With a multidisciplinary approach and judicious use of ancillary studies, FNAB represents a highly accurate and cost-effective technique for the diagnosis of pediatric bone and soft tissue tumors, especially sarcomas, and should be considered as a viable diagnostic technique for pediatric therapeutic protocols.

Histogenetic relations between giant cell fibroblastoma and dermatofibrosarcoma protuberans. CD34 staining showing the spectrum and a simulator

The authors describe three lesions that provide further evidence for a close, possibly histogenetic relation between giant cell fibroblastoma and dermatofibrosarcoma protuberans. The first case involves a dermatofibrosarcoma protuberans that contained a single giant cell fibroblastoma-like focus of multi-nucleate giant cells. A second tumor, a giant cell fibroblastoma, recurred 6 years later as a dermatofibrosarcoma protuberans. In the third lesion, there was a juxtaposition and co-mingling of dermatofibrosarcoma protuberans and giant cell fibroblastoma within the same primary lesion. In all cases, both the giant cell fibroblastoma areas and dermatofibrosarcoma protuberans areas stained positively with CD34. A fourth case, a dermatofibrosarcoma protuberans infiltrated skeletal muscle, creating giant cell fibroblastoma-like giant cell mimics--a result of skeletal muscle degeneration or atrophy with nuclear conglomeration. The latter giant cells failed to express CD34 but did show immunoreactivity with desmin. These findings support the concept that giant cell fibroblastoma and dermatofibrosarcoma protuberans probably represent a histologic spectrum of a single CD34 positive (perhaps, dermal dendrocytic) neoplasm, a conclusion supported by a recently cloned t(7;22) breakpoint demonstrated in both neoplasms.

Epithelioid hemangioendothelioma of bone and soft tissue: a fine-needle aspiration biopsy study with histologic and immunohistochemical confirmation

We retrospectively reviewed two fine-needle aspiration biopsy (FNAB) specimens from two patients with histologically confirmed epithelioid hemangioendothelioma (EH). Both patients were men, ages 79 and 39 years; their primary tumors arose in the soft tissues of the mediastinum and within the proximal tibia, respectively. The former patient had symptoms of superior vena cava syndrome; multicentric intraosseous lesions involved the proximal tibia of the latter patient. All cytologic smears were hypercellular and composed of mostly disassociated single cells and small aggregates of ovoid to polygonal-shaped epithelioid cells. Nuclei were variable, ranging from ovoid and reniform to round and polylobated and surrounded by an abundant amount of dense cytoplasm. Binucleated epithelioid neoplastic cells were frequent. Nuclear pleomorphism ranged from slight to moderate, and small solitary to multiple nucleoli were identified within the majority of tumor cells. Rare neoplastic cells with a single, sharply demarcated intracytoplasmic vacuole and intranuclear cytoplasmic pseudoinclusions were observed in the smears of one tumor. Metachromatic stromal fragments, probably representing hyalinized chondromyxoid stroma, were seen in the other tumor. Neither case was recognized initially on FNAB as EH. Immunohistochemically, sections from the surgical biopsy specimens of both cases showed diffuse and strong immunopositivity for the endothelial marker CD31. Although the cytomorphology of EH appears distinct, clinicoradiologic correlation is essential, and immunohistochemistry may be helpful to avoid misdiagnoses.