Parachordoma is immunohistochemically and cytogenetically distinct from axial chordoma and extraskeletal myxoid chondrosarcoma

Keratin-positive fibrotic extraskeletal myxoid chondrosarcoma: a close mimic of myoepithelial tumour

AIMS

Extraskeletal myxoid chondrosarcoma (EMC) is a rare form of adult sarcoma with distinct histology and NR4A3 gene fusion. Immunohistochemically, EMCs are variably positive for S100 protein and neuroendocrine markers. Unlike histologically similar soft-tissue myoepithelial tumours, keratin expression is rare. Prompted by two recent EMC cases with diffuse keratin expression, we investigated the expression of epithelial markers in a molecularly confirmed cohort of EMC and identified two additional similar cases.

METHODS AND RESULTS

Four keratin-positive EMCs occurred in one man and three women aged 46-59 years. All tumours displayed nonclassic histology with prominent stromal fibrosis, and keratin AE1/AE3 was expressed either diffusely (N = 2) or focally (N = 2). In one tumour, keratin expression was limited to the sclerotic area. All tumours coexpressed epithelial membrane antigen and two additionally expressed S100 protein or glial fibrillary acidic protein. All tumours harboured NR4A3 fusions, including TAF15::NR4A3 (N = 1) and EWSR1::NR4A3 (N = 3). Two cases were initially considered as most consistent with myoepithelial tumours based on widespread stromal fibrosis and keratin expression. DNA methylation analysis classified two tumours tested as EMCs.

CONCLUSIONS

We identified a small subset of EMCs characterised by keratin expression and prominent stromal fibrosis. This histological pattern must be recognised in the differential diagnosis of myoepithelial tumours because misclassification may lead to the erroneous prediction of tumour behaviour and may alter patient management. NR4A3 genetic analysis should be considered even in the face of keratin expression and prominent stromal fibrosis.

Primary intracranial extraskeletal myxoid chondrosarcoma: A case report and review of literature

BACKGROUND

Primary intracranial extraskeletal myxoid chondrosarcoma (EMC) is an extremely rare low- to intermediate-grade malignant soft tissue sarcoma, and only 15 cases have been reported in the literature. Due to its rarity, clinical data and research on this tumor type are extremely limited, the pathogenesis and histological origin are still unclear, and the diagnostic and standard clinical treatment strategies for intracranial EMC remain controversial and undefined.

CASE SUMMARY

We reported a case of a 52-year-old male who was admitted to the hospital with headache and dizziness for 1 mo, and his health status deteriorated during the last week. CT of the head showed a well-defined low-density lesion situated in the left cavernous sinus. Brain magnetic resonance imaging (MRI) showed a 3.4 cm × 3.0 cm sized, well-defined, round-shaped and heterogeneously enhanced lesion located in the left cavernous sinus. The entire lesion was removed via supratentorial craniotomy and microsurgery. Postoperative pathological diagnosis indicated primary intracranial EMC. Subsequently, the patient underwent 45 Gy/15 F stereotactic radiotherapy after discharge. At present, it is 12 mo after surgery, with regular postoperative follow-up and regular MRI examinations, that there are no clinical symptoms and radiographic evidence indicating the recurrence of the tumor, and the patient has returned to normal life.

CONCLUSION

Currently, the most beneficial treatment for primary intracranial EMC is gross total resection combined with postoperative radiotherapy. Long-term follow-up is also necessary for patients.

Notochordal Tumors

This review provides an overview of the spectrum of tumors showing notochordal differentiation. This spectrum encompasses benign entities that are mostly discovered incidentally on imaging, reported as benign notochordal cell tumor, usually not requiring surgical intervention; slowly growing and histologically low-grade tumors referred to as conventional chordoma but associated with a significant metastatic potential and mortality; and more aggressive disease represented by histologically higher-grade tumors including dedifferentiated chordoma, a high-grade biphasic tumor characterized by a conventional chordoma juxtaposed to a high-grade sarcoma, usually with a spindle or pleomorphic cell morphology, and associated with a poor prognosis and poorly differentiated chordoma.

Primary intracranial extra-skeletal myxoid chondrosarcoma of right lateral ventricle with EWSR1 gene fusion: a case report and review of literature

Background

Primary intracranial malignancies with extra-skeletal myxoid chondrosarcoma (EMC) features are extremely rare. EMC constitutes a distinct genomic entity characterised by reciprocal translocation of fusion genes, most commonly EWS RNA Binding Protein 1 (EWSR1) in 22q12 with Nuclear Receptor Subfamily 4 Group A Member 3 (NR4A3) in 9q2-q31.1. It is reported to have a high propensity for local recurrence and has potential for metastasis. So far in 28 years since its first description, only 17 cases of primary intracranial EMC were reported in literature. This would be the second case of intraventricular origin and first case from lateral ventricle.

Case presentation

A 27-year-old male presenting with complaints of headache, seizures and pain in neck was diagnosed to have a mass lesion in right lateral ventricle in Magnetic Resonance Imaging of brain. He underwent right parieto-occipital craniotomy with total excision of the lesion. Initial histopathological examination was reported as Ependymoma, WHO grade II. However, blocks and slides review with immunohistochemistry (IHC) markers revealed neoplastic aetiology with extensive myxoid changes. Hence, fluorescent in-situ hybridisation (FISH) testing was done with EWSR1 break apart probe, which demonstrated EWSR1 break apart signals. Therefore, correlating the clinical findings with morphology, IHC and FISH, the diagnosis of primary intracranial EMC was rendered. Patient received adjuvant external beam radiation of 54 Gy in 30 fractions to the post-op region. At 29-month follow-up, there was no evidence of disease recurrence.

Conclusions

Owing to the rarity of the condition, there are no standard treatment guidelines available for primary intracranial EMC. A combined treatment approach with surgery followed by adjuvant radiotherapy provides good local control with less morbidity.

Chordoma: A Review and Differential Diagnosis

CONTEXT.—

Chordomas are uncommon malignant neoplasms with notochordal differentiation encountered by neuropathologists, bone/soft tissue pathologists, and general surgical pathologists. These lesions most commonly arise in the axial skeleton. Optimal therapy typically involves complete surgical resection, which is often technically difficult owing to the anatomic location, leading to a high rate of recurrence. Lesions have been generally resistant to radiation and chemotherapy; however, experimental studies involving targeted therapy and immunotherapy are currently underway.

OBJECTIVE.—

To summarize the clinical and pathologic findings of the various types of chordoma (conventional chordoma, dedifferentiated chordoma, and poorly differentiated chordoma), the differential diagnosis, and recent advances in molecular pathogenesis and therapeutic modalities that are reliant on accurate diagnosis.

DATA SOURCES.—

Literature review based on PubMed searches containing the term "chordoma" that address novel targeted and immunomodulatory therapeutic modalities; ongoing clinical trials involved in treating chordoma with novel therapeutic modalities identified through the Chordoma Foundation and ClinicalTrials.gov; and the authors' practice experience combined with various authoritative texts concerning the subject.

CONCLUSIONS.—

Chordoma is a clinically and histologically unique malignant neoplasm, and numerous diagnostic considerations must be excluded to establish the correct diagnosis. Treatment options have largely been centered on surgical excision with marginal results; however, novel therapeutic options including targeted therapy and immunotherapy are promising means to improve prognosis.

Incidental findings in and around the prostate on prostate MRI: a pictorial review

Prostate MRI has seen rapid growth in use in recent years as an advanced diagnostic modality to detect focal areas of clinically significant prostate cancer, to identify an area for targeted biopsy and to guide management and surveillance. The increase in use has also led to increased diagnosis of incidental lesions arising from structures around the prostate. These incidental findings may be related to the genitourinary system or non- genitourinary system and may have a benign aetiology which needs no additional follow-up, or it may require surveillance and management. The field of view in a multiparametric prostate MRI includes other pelvic organs, neurovascular bundles, bowel, lymph nodes and bones. Being familiar with standard MRI characteristics and a sound knowledge of anatomy of the prostate and surrounding structures can help in distinguishing normal anatomy from pathology. Given that patients undertaking a prostate MRI are usually a cohort with increased anxiety from their known or suspicion of prostate cancer, it is important that radiologists are familiar with these common incidental findings to minimise anxiety to the patient, have a well-informed discussion with the referring clinician and reduce costs associated with unnecessary further testing and follow-up of benign incidental findings. Additionally, being able to diagnose more serious incidental pathologies early can be life-saving and potentially significantly alter patient management.

Update on SWI/SNF-related gynecologic mesenchymal neoplasms: SMARCA4-deficient uterine sarcoma and SMARCB1-deficient vulvar neoplasms

Our knowledge regarding the role of genes encoding the chromatin remodeling switch/sucrose non-fermenting (SWI/SNF) complex in the initiation and progression of gynecologic malignancies continues to evolve. This review focuses on gynecologic tumors in which the sole or primary genetic alteration is in SMARCA4 or SMARCB1, two members of the SWI/SNF chromatin remodeling complex. In this review, we present a brief overview of the classical example of such tumors, ovarian small cell carcinoma of hypercalcemic type, and then a detailed review and update of SMARCB1-deficient and SMARCA4-deficient tumors of the uterus and vulva.

Soft Tissue Special Issue: Chondroid Neoplasms of the Skull

Clinically, radiologically, and pathologically, chondroid neoplasms of the skull can be diagnostically challenging due to overlapping features in each of these domains. Compounding the problem for the pathologist, there is also significant morphologic, immunophenotypic, and molecular genetic overlap between benign and malignant cartilaginous lesions, and the majority of these lesions are encountered quite rarely in routine surgical pathology practice. Each of these factors contribute to the diagnostic difficulty posed by these lesions, highlighting the importance of radiologic-pathologic correlation in the diagnosis. This review is intended to provide an update for surgical pathologists on some of the most commonly encountered chondroid neoplasms in the skull, and includes the following lesions: chondromyxoid fibroma, synovial chondromatosis, chondrosarcoma and variants, and chordoma and variants. For each of these lesions, the differential diagnosis and useful ancillary tests will be discussed in the context of a broad range of additional primary and secondary lesions.

Intra-articular extra-axial chordoma of the wrist: a case report with review of the current literature

Chordomas are rare bone malignancies that are thought to arise from remnants of the notochord and usually are located in the axial skeleton. Immunophenotypical matching neoplasms primarily found in appendicular locations, referred to as extra-axial chordoma, are rarely encountered by radiologists, surgeons, and pathologists. Only a few of these cases have been described in the literature with only one intra-articular case with involvement of the knee joint. We present the first case of an intra-articular extra-axial chordoma of the wrist. Diagnostic imaging patterns were initially ambiguous and histopathological reprocessing was crucial in order to determine the diagnosis of an intra-articular neoplasm with co-expression of cytokeratins, S-100 protein, and brachyury.

Parachordoma: A Case Report

Parachordoma is a very rare soft tissue tumor with histological features similar to chordoma and chondrosarcoma. It should be distinguished from metastatic chordoma and extraskeletal myxoid chondrosarcoma because of its different treatment and prognosis. In this paper we report one case of parachordoma in a 20-year-old female patient. The tumor occurred in the subcutaneous tissue of the left hand as a painless, fixed, slow-growing mass. Pathologic analysis revealed a tumor composed of lobules of cells with variably vacuolated cytoplasm (physaliphorous cells) separated by fibrous septa, predominantly arranged in peculiar small or large alveolar structures. Immunohistochemistry showed positive staining of the tumor cells with cytokeratin 8/18, S-100 protein and vimentin. The patient is well and without recurrence 20 months after surgery.

Chordoma of the Head and Neck: A Review

Chordoma is a rare malignant bone tumor that can arise anywhere along the central neural axis and many involve head and neck sites, most commonly the skull base. The relative rarity of these tumors, combined with the complex anatomy of the head and neck, pose diagnostic challenges to pathologists. This article describes the pertinent clinical, pathologic, and molecular features of chordomas and describes how these features can be used to aid in formulating a differential diagnosis. Emphasis is placed on key diagnostic pitfalls and the importance of incorporating immunohistochemical information into the diagnosis.

Myoepithelial Carcinoma: The Role of Radiation Therapy. A Case Report and Analysis of Data From the Surveillance, Epidemiology, and End Results (SEER) Registry

PURPOSE/OBJECTIVE

The role of radiation therapy in the treatment of myoepithelial carcinoma (MC) is unknown. We present a case of a high-grade soft-tissue MC in a pediatric patient and retrospectively examine the effect of postoperative radiation on survival in patients with MC.

MATERIALS AND METHODS

Our patient was treated with 4 cycles of ifosfamide, cisplatin, and etoposide followed by 3 cycles of ifosfamide vincristine and etoposide. Radiation was delivered to a total dose of 5580 cGy in 180 cGy/fraction to the surgical bed with a 2 cm margin starting after the third cycle of chemotherapy. The Surveillance, Epidemiology, and End Results (SEER) registry database was queried for cases of surgically resected MC. Retrospective analysis was performed with the endpoint of overall survival (OS).

RESULTS

Two hundred thirty-four cases of MC were identified; for 62 of these cases, the grade of the tumor wasidentified. Of these 62 patients, 27 received postoperative radiation. OS was improved with adjuvant radiation therapy in patients with grade III or IV MC (P<0.01) as determined by the log-rank test.

CONCLUSIONS

This analysis of SEER data showed an OS benefit with adjuvant radiation therapy in the treatment of high-grade MC. Physicians should report all cases of MC to improve clinical decision making in the treatment of this rare disease.

Extra-axial chordomas

INTRODUCTION

A chordoma is a slow growing malignant tumour of notochordal origin. A tumour with histological features that are identical to those of a chordoma may arise outside the axial skeleton. To date, there is little in the literature documenting their clinical course.

METHODS

Our large orthopaedic oncology database was used to document the clinical course of extra-axial chordoma.

RESULTS

Over a 30-year period, 131 patients diagnosed with a chordoma were treated at our unit. Only three (2.3%) of these cases were extra-axial chordomas: one in the femur, one in the ulna and one in the proximal fibula. All underwent surgical resection.

CONCLUSIONS

In view of the rarity of this tumour and the difficulty in confirming its diagnosis, we suggest that any suspected case is discussed with a specialist sarcoma multidisciplinary team so that the correct diagnosis can be achieved and treatment tailored accordingly.

Epithelioid Sarcoma: Diagnostic Features and Genetics

Epithelioid sarcoma (ES) is a rare, aggressive soft-tissue neoplasm of uncertain differentiation, characterized by nodular aggregates of epithelioid cells, which are immunoreactive to cytokeratins (CKs) and epithelial membrane antigen, and often for CD34. It has a propensity for multifocal disease at presentation, local recurrence, and regional metastasis. These are aggressive neoplasms with particularly poor prognosis after regional or distant metastatic disease, for which surgical resection is still the mainstay of treatment, and options for patients with metastatic disease remain undefined. There are 2 distinct variants: classic ES, which typically presents as a subcutaneous or deep dermal mass in the distal extremities of young adults and comprises nodular distributions of relatively uniform epithelioid cells with central necrosis, and the proximal variant, which has a predilection for proximal limbs and limb girdles and the midline of the trunk, which is composed of sheets of larger, more atypical cells with variable rhabdoid morphology. Both classic and proximal-type ESs are associated with the loss of SMARCB1/INI1 protein expression, but appear otherwise molecularly relatively heterogeneous. We review classic and proximal-type ES, discussing morphology, immunohistochemical and genetic findings, the differential diagnosis, and the future potential for targeted therapies.

Contemporary diagnostics: sarcoma pathology update

Sarcoma diagnosis continues to evolve as new information is discovered. Certain tumors have been downgraded (dermal leiomyosarcoma) and an atypical category designed for others. Recently entities include myxoinflammatory fibroblastic sarcoma, myoepithelioma, and pseudomyogenic hemangioendothelioma. The terms malignant fibrous histiocytoma and hemangiopericytoma are outdated. New immunostains (STAT6, SOX10, ERG) add diagnostic specificity, and new risk assessment models are described for sarcomas where grading and staging has failed to provide adequate prognosis.

Primary intracranial Parachordoma: An unusual tumor in brain

Background:

Parachordomas are rare soft tissue tumors commonly occurring in limbs, chest, Abdomen, and back. The World Health Organization (WHO) classification includes parachordomas in the same group as mixed tumors and myoepitheliomas. Exact histogenesis of this tumor is unclear.

Case Description:

A 52-year-old male presented with headache and blurring of vision since one month. Preoperative computed tomography (CT) scan of brain revealed left parieto-occipital tumor extending up to the trigone. Total excision of the tumor was done. Histopathologically, the tumor was composed of relatively uniform cells with eosinophilic cytoplasm in a myxoid stroma and with cartilaginous and osseous metaplasia. The tumoral cells were immunoreactive for cytokeratin, epithelial membrane antigen (EMA), S-100, and vimentin. The constellation of findings revealed the tumor to be parachordoma. Magnetic resonance imaging (MRI) brain during follow-up at one year showed no recurrent tumor. No adjuvant therapy was given to this patient.

Conclusion:

This is the first reported case of primary intracranial parachordoma. It is difficult to diagnose the lesion preoperatively by imaging alone. Long-term follow-up is necessary in view of few reports in literature of recurrence and metastasis, of parachordomas in other anatomical locations.

Myoepithelial tumor of soft tissue: histology and genetics of an evolving entity

Myoepithelial neoplasms represent a heterogeneous group of tumors of which classification is incomplete and evolving. Those of the soft tissues often form genetically distinct subgroups that differ from those arising within salivary glands. Soft-tissue myoepithelial tumors (including mixed tumors that show true glandular or ductal differentiation) exhibit a spectrum of different morphologic patterns, making them difficult to distinguish from a variety of other neoplasms. They have been increasingly shown to harbor genetic fusions involving EWSR1 and partner genes that are not seen in the well-characterized tumor classes involving EWSR1 translocations. We review the spectrum of soft-tissue myoepithelial tumors, discussing recent immunohistochemical and genetic findings and the differential diagnosis.

Primary intestinal and vertebral chordomas in laboratory zebrafish (Danio rerio)

Chordomas are uncommon neoplasms arising from notochord remnants, most commonly occurring in the axial skeleton. Extraskeletal soft tissue chordomas are rare primary tumors, and primary alimentary tract chordomas have not been reported. Herein we report 24 cases of spontaneous primary intestinal chordomas in zebrafish, as well as 9 spontaneous vertebral chordomas. Both intestinal and vertebral tumors showed invasive behavior, although more commonly in the latter. In all cases of primary intestinal chordomas, there was no axial or peripheral skeletal or other nonvisceral involvement. Although uncommon, intestinal chordomas represent a unique background lesion in aged zebrafish.

Recently characterized soft tissue tumors that bring biologic insight

Previously unrecognized but clinicopathologically (and often molecularly) distinct types of soft tissue tumor continue to be characterized, allowing wider recognition, more consistent application of diagnostic criteria, more reliable prediction of tumor behavior and enhancement of existing classification schemes. Examples of such 'entities' that have become much better understood over the past decade or so include deep 'benign' fibrous histiocytoma, hemosiderotic fibrolipomatous tumor, PEComa, spindle cell liposarcoma, myoepithelial tumors of soft tissue and spindle cell/sclerosing rhabdomyosarcoma. These tumor types, as well as the insights which they have engendered, are briefly reviewed here.

Recurrent skeletal extra-axial chordoma confirmed with brachyury: imaging features and review of the literature

A small number of tumors bearing histological resemblance to axial chordoma arising from the bone or soft tissue outside the axial skeleton have been reported. These lesions have historically been referred to as parachordoma, chordoma periphericum (CP), or extra-axial chordoma (EAC). With the introduction of the immunohistochemical stain brachyury, a sensitive and specific marker for notochordal origin, chordomas arising in extra-axial locations (i.e., CP, EAC), are now diagnosed with more accuracy and distinguished from parachordoma, which resembles chordoma on histology. The distinction between EAC and parachordoma is clinically important because EAC confirmed by immunoreactivity for brachyury tends to grow and recur with local bone destruction. Prior to the introduction of brachyury, the diagnosis of EAC was challenging and therefore the imaging features of EAC have not been comprehensively described. We report two cases of recurrent EAC confirmed by the expression of brachyury arising from the distal femur and distal tibia and describe the imaging findings from radiography and MRI at initial diagnosis and at recurrence.

Parachordoma of soft tissues of the arm: a very rare tumour

Parachordoma is an infrequent neoplasm that bears some histologic resemblance to chordoma. It affects both sexes, occurs typically during the fourth decade of life, and tends to present as a slow-growing painless mass at the level of the soft tissues of the extremities. Diagnosis should be based on immunohistochemical and cytogenetic studies, as the findings of imaging techniques are often unspecific. Although it is considered a benign lesion, its behavior tends to be locally aggressive, with reports of a recurrence rate of up to 20% and of several cases of metastasis. Fewer than 60 cases have been published in the English-speaking literature. In this paper we present the case of a 32-year-old male with a two-year history of parachordoma in the right wrist.

Imprint cytology of soft tissue myoepithelioma: a case study

Soft tissue myoepithelioma is a rare neoplasm composed of myoepithelial cells. Here, we describe the cytologic features of soft tissue myoepithelioma arising on the right forearm in an 18-year-old man. The excised tumor (3.0×1.8×1.5 cm) was well-demarcated, yellow-gray, soft, and myxoid. The cytologic smears showed round to spindle, epithelioid, and plasmacytoid cells in the myxoid background. The nuclei were uniform, round to ovoid, with finely distributed chromatin and eosinophilic or pale cytoplasm. The tumor cells demonstrated immunoreactivity for cytokeratin (AE1/AE3), epithelial membrane antigen, S100 protein, and glial fibrillary acidic protein. Electron microscopy showed intermediate filaments, desmosomes, and basal lamina.

Cutaneous neoplasms showing EWSR1 rearrangement

Rearrangements of the EWSR1 gene are found in an increasing number of human neoplasms, including several tumors that can involve the skin: Ewing sarcoma/primitive neuroectodermal tumor, angiomatoid (malignant) fibrous histiocytoma, myoepithelioma of soft tissue, and clear cell sarcoma. Although these tumors share this common genetic link, they have very different clinical features, morphology, immunophenotype, and sometimes fusion gene partners; these will be the subjects of this review.

Huge pelvic parachordoma: fine needle aspiration cytology and histological differential diagnosis

Parachordoma is an extremely rare soft tissue tumor of unknown lineage. Parachordoma develops most often on the extremities. Only 2 cases have been reported as pelvic parachordoma. A 46-year old Egyptian woman with a huge painful pelvic mass was found to have a parachordoma with ectopic pelvic right kidney. There is only one report in the literature of fine needle aspiration cytology in this setting. The microscopic picture of parachordoma is not new to pathologists but the gross picture of this rare tumor has not previously been published; not even in the World Health Organization classification of soft tissues tumors. Diagnosis was confirmed by immunohistochemistry. The patient is in good clinical condition without any evidence of recurrence or metastasis after 84 months of follow up.

NR4A3 rearrangement reliably distinguishes between the clinicopathologically overlapping entities myoepithelial carcinoma of soft tissue and cellular extraskeletal myxoid chondrosarcoma

Myoepithelial carcinoma of soft tissue (MEC) and cellular extraskeletal myxoid chondrosarcoma (cEMC) share striking similarities. In this paper, we compare ten MECs with five cEMCs. MEC patients had an equal gender distribution. The age range was 15–76 years (mean, 42 years). Tumours were located on extremities, pelvic girdle, vulva and neck. Follow-up, available for nine patients, ranged from 4 to 85 months (mean, 35 months). Five patients were alive without evidence of disease, two were alive with disease and two died 8 months after the initial diagnosis. cEMCs were from three males and two females with an age range of 37–82 years (mean, 57 years); they presented in extremities, shoulder and paravertebral/cervical. Follow-up, available for four patients, ranged from 6 to 220 months (mean, 61 months). All patients were alive, two with recurrences and/or metastases and two without evidence of disease. Morphologically, the distinction between these two entities was difficult since all cases exhibited features typically seen in myoepithelial tumours. Immunohistochemically, MECs expressed pan-keratin (80 %), epithelial membrane antigen (EMA; 57 %), S100 (50 %), alpha-smooth muscle actin (ASMA; 75 %), calponin (67 %) and p63 (25 %). S100 and EMA were expressed in 40 % of cEMC cases respectively with additional immunoreactivity for p63, ASMA and glial fibrillary acidic protein in one case. Pan-keratin was negative in all neoplasms. NR4A3 rearrangement was present in four of four cEMCs and in none of the MECs. In contrast, three of nine (33 %) MECs and four of five (80 %) cEMCs showed an EWSR1 rearrangement. In summary, MECs and cEMCs share clinical, morphological, immunohistochemical and genetic characteristics. The pathognomic rearrangement of NR4A3 is a useful diagnostic feature in identifying cEMCs.

Primary pulmonary myxoid sarcoma with EWSR1-CREB1 fusion: a new tumor entity

We present clinicopathologic data on 10 pulmonary myxoid sarcomas, which are defined by distinctive histomorphologic features and characterized by a recurrent fusion gene, that appear to represent a distinct tumor entity at this site. The patients [7 female, 3 male; aged 27 to 67 y (mean, 45 y)] presented with local or systemic symptoms (n=5), symptoms from cerebral metastasis (1), or incidentally (2). Follow-up of 6 patients showed that 1 with brain metastasis died shortly after primary tumor resection, 1 developed a renal metastasis but is alive and well, and 4 are disease free after 1 to 15 years. All tumors involved pulmonary parenchyma, with a predominant endobronchial component in 8 and ranged from 1.5 to 4 cm. Microscopically, they were lobulated and composed of cords of polygonal, spindle, or stellate cells within myxoid stroma, morphologically reminiscent of extraskeletal myxoid chondrosarcoma. Four cases showed no or minimal atypia, 6 showed focal pleomorphism, and 5 had necrosis. Mitotic indices varied, with most tumors not exceeding 5/10 high-power fields. Tumors were immunoreactive for only vimentin and weakly focal for epithelial membrane antigen. Of 9 tumors, 7 were shown to harbor a specific EWSR1-CREB1 fusion by reverse transcription-polymerase chain reaction and direct sequencing, with 7 of 10 showing EWSR1 rearrangement by fluorescence in situ hybridization. This gene fusion has been described previously in 2 histologically and behaviorally different sarcomas: clear cell sarcoma-like tumors of the gastrointestinal tract and angiomatoid fibrous histiocytomas; however, this is a novel finding in tumors with the morphology we describe and that occur in the pulmonary region.

Benign notochordal lesions of the axial skeleton: a review and current appraisal

At the 1996 meeting of the International Skeletal Society, an idea was put forth that there existed symptomatic lesions of the axial skeleton, morphologically different from chordoma, that were consistent with benign notochordal remnants (rests). A review of the embryological basis for this concept is made, along with an analysis of these lesions, termed giant notochordal rests or benign notochordal cell tumors, that have been reported in the intervening 15 years, with a commentary on their relationship, if any, to chordoma.

Intraneural parachordoma of the arm with regional metastases

Parachordoma is a rare tumor, with fewer than 100 cases reported. We present an unusual presentation of a long tumor tracking along the median nerve, with regional metastasis to the axillary nodes in a 67-year-old woman. The tumor extended from the wrist proximally along the forearm to the elbow, coursing intraneurally along the median nerve. We present this case due its rarity, interesting radiographic appearance, and atypical presentation.

Childhood Carcinoma

Carcinoma in children differs from that occurring in adults. It is far rarer and represents only a small fraction of all pediatric cancer diagnoses. Pediatric sarcomas were among the first tumors in which recurrent chromosomal aberrations were discovered. Once defined, these recurrent aberrations, many of them translocations, became incorporated into the pathologist's diagnostic armamentarium. In the past several years, defining chromosomal rearrangements have been identified in pediatric carcinomas as well, and this has become a new frontier in pathologic diagnosis. This article provides an overview of pediatric carcinoma as well as a detailed review of selected types of carcinoma that in particular can present diagnostic difficulty to the practicing pathologist and illustrate new and emerging concepts in pediatric carcinoma.

Derivation and characterization of an extra-axial chordoma cell line (EACH-1) from a scapular tumor

BACKGROUND

Extra-axial chordomas are rare low-grade malignant tumors thought to arise from notochordal remnants in the extra-axial skeleton. Few studies have been done on this neoplasm because of its rarity. In addition, there is a lack of a good in vitro model on which to perform more characterization.

METHODS

We describe a twenty-eight-year-old man with a mass in the right scapula. Cytomorphology and immunohistochemistry, including brachyury staining, were used to formulate the final diagnosis. A fragment of the tumor was placed in culture, and cells obtained were injected subcutaneously in an immunocompromised mouse. From the tumor developed in mice, a cell line has been derived and characterized by fluorescence-activated cell-sorting analysis, karyotyping, clonogenicity, and cell and tumor growth curves.

RESULTS

Cytomorphology on the tumor showed nests of round cells with vacuoles and also physaliferous-like cells with uniform nuclei. Immunochemistry revealed a tumor positive for vimentin, moderately positive for S-100 and cytokeratin AE1/AE3, weakly positive for epithelial membrane antigen, and negative for p63 and cytokeratin (CK)-7. Further analysis revealed the tumor was diffusely and strongly positive for brachyury. The cell line derived from the tumor showed rapid doubling-time, a strong expression of mesenchymal cell surface markers, a karyotype of diploid or hypotetraploid clones with numerous chromosomal aberrations, and the ability to form colonies without attachment and to form tumors in immunocompromised mice.

CONCLUSIONS

The diagnosis of the extra-axial chordoma is difficult but can be resolved by the detection of a strong brachyury expression. In addition, the derivation of a human extra-axial chordoma cell line could be a useful tool for the basic research of this rare neoplasm.

Possible parachordoma in a dog

CASE HISTORY

A 15-mm diameter mass developed in the S/C tissue overlying the right lateral gluteal muscle of a 6(1/2)-year-old female Flat-coated Retriever.

PATHOLOGICAL FINDINGS

Cytological preparations following aspiration of the mass were highly cellular and consisted of a population of large polygonal cells containing single to multiple nuclei, large prominent nucleoli, and intracytoplasmic vacuoles. Histologically, the neoplasm consisted of similar large cells surrounded by thick fibrous connective tissue trabeculae. The large polygonal cells reacted positively with antibodies against vimentin, low- and high-molecular-weight variants of cytokeratin (AE1/AE3), but not with antibodies to desmin or glial fibrillary acidic protein (GFAP).

DIAGNOSIS

The clinical, gross, histological and immunohistochemical findings are similar to those reported for parachordomas in humans. Neither recurrence nor metastases were noted 18 months after surgical excision of the mass.

CLINICAL RELEVANCE

This is the first reported case of a possible parachordoma in a dog, a benign tumour with cytological features of malignancy.

Myoepithelioma within the carpal tunnel: a case report and review of the literature

Myoepitheliomas of the extremity are rare and usually benign, while a minority display malignant features. This case demonstrates the diagnosis and management of myoepithelioma within the carpal tunnel. Clinical and radiological tumour features were evaluated. Hematoxylin and eosin stained tumour sections were examined, and immunohistochemistry was performed. Histology revealed a nodular mass of epithelioid cells in clusters within a myxoid/chondroid stroma. No mitoses were noted. Cytokeratins, neuron-specific enolase, synaptophysin, glial fibrillary acidic protein, and S100 were positive on immunohistochemistry. A literature review revealed very few prior reports of myoepithelioma in the wrist, and limited data concerning any relationship between recurrence and quality of surgical margins. In this case, wide local excision would have significantly compromised dominant hand function, and therefore a marginal excision was deemed appropriate in the context of bland histological features. Surgical margins noted in future case reports will aid clinical decision making.

Heterogeneous genetic profiles in soft tissue myoepitheliomas

Myoepithelioma, mixed tumor and parachordoma are uncommon soft tissue tumors thought to represent morphological variants of a single tumor type. The genetic basis of these neoplasms is poorly understood. However, they morphologically resemble mixed tumor of the salivary glands (also known as pleomorphic adenoma), a tumor characterized by deregulated expression of PLAG1 or HMGA2. To evaluate a possible genetic relationship between these soft tissue and salivary gland tumors, PLAG1 expression levels and the genomic status of PLAG1 and HMGA2 were investigated in five soft tissue myoepitheliomas and one pleomorphic adenoma. In addition, all tumors were cytogenetically investigated and whole genome DNA copy number imbalances were studied in five of them. The genetic profiles were heterogeneous and the only aberration common to all soft tissue myoepitheliomas was a minimally deleted region of 3.55 Mb in chromosome band 19p13. Recurrent deletion of CDKN2A suggests that inactivation of this tumor suppressor gene is pathogenetically important in a subset. Furthermore, PLAG1 rearrangement was found in a soft tissue tumor from a patient previously treated for a salivary pleomorphic adenoma, indicating either metastasis of the salivary gland lesion or that some soft tissue tumors develop through the same mechanisms as their salivary gland counterparts.

Case report: parachordoma of soft tissues of the arm

Parachordoma, or myoepithelioma, is a very rare tumor histologically resembling chordoma but occurring in the nonaxial soft tissues. It typically has an indolent nature, with occasional late recurrence and even rare metastases. Review of existing literature reveals a male predilection, with the tumor typically occurring in the fourth decade of life in the lower extremity. It typically is managed with wide resection. We report the case of a 60-year-old woman with a right distal upper arm parachordoma treated with wide resection of the tumor.

Parachordoma of the gastric serosa: report of a myxoid mimicry in an unusual location

The authors report a case of an incidentally discovered myxoid stromal tumor occurring in the outer wall of the stomach of a 65-year-old woman. The tumor was phenotypically consistent with parachordoma (or myoepithelioma), showing a chordoid microscopic appearance of tumor cells loosely arranged within a myxoid or hyaline background. Immunoreactivity for high-molecular-weight keratins, S100 protein, and vimentin was detected. In this report, the authors address the differential diagnosis of parachordoma and the unusual location of this neoplasm.