Genomic and Transcriptomic Underpinnings of Melanoma Genesis, Progression, and Metastasis

Melanoma is a deadly skin cancer with rapidly increasing incidence worldwide. The discovery of the genetic drivers of melanomagenesis in the last decade has led the World Health Organization to reclassify melanoma subtypes by their molecular pathways rather than traditional clinical and histopathologic features. Despite this significant advance, the genomic and transcriptomic drivers of metastatic progression are less well characterized. This review describes the known molecular pathways of cutaneous and uveal melanoma progression, highlights recently identified pathways and mediators of metastasis, and touches on the influence of the tumor microenvironment on metastatic progression and treatment resistance. While targeted therapies and immune checkpoint blockade have significantly aided in the treatment of advanced disease, acquired drug resistance remains an unfortunately common problem, and there is still a great need to identify potential prognostic markers and novel therapeutic targets to aid in such cases.

Panniculitis in a patient with pathologic complete response to talimogene laherparepvec treatment for recurrent, in-transit melanoma

Talimogene laherparepvec (T-VEC) is a novel intralesional oncolytic genetically modified herpes simplex virus type 1 vector for the treatment of unresectable cutaneous, subcutaneous, and nodal melanoma. Although immunological therapies such as T-VEC offer therapeutic promise, they carry a risk of immune-related adverse events (irAEs), the full spectrum of which is incompletely understood. We report a 63-year-old previously healthy man with cutaneous melanoma of the right ankle and progressive right lower extremity in-transit metastases despite systemic therapy with immunomodulatory and molecularly targeted treatments. T-VEC treatment resulted in a complete pathologic response on scouting biopsies. Biopsy of the right lateral calf showed lobular and septal panniculitis with lymphoplasmacytic infiltrate and lipophages. Gomori methenamine silver (GMS) stain and acid-fast bacilli (AFB) stains were negative, and no polarizable foreign material was noted. T-VEC was discontinued due to complete pathologic response and, in part, concern for development of irAEs including this panniculitis and an early concomitant autoimmune colitis. This case highlights a previously unreported irAE with this novel treatment for advanced cases of melanoma.

Granulocytic Sarcoma

Because of shared histologic and clinical features, granulocytic sarcoma (GS) may be confused with B- and T cell malignant lymphomas. Antibodies to myeloperoxidase, lysozyme, CD 15, and other determinants may correctly identify GS but are usually not part of the standard panels employed to evaluate a suspected non-Hodgkin's lym phoma. At the authors' institutions, these typically include reagents to CD20, CD43, CD45, CD45RO, and MB2. In this analysis, well-documented cases of GS and histologi cally similar lymphomas were assessed using a standard immunohistologic antibody panel employed in evaluation of putative lymphomas. In addition, antibodies to lyso zyme, myeloperoxidase, CD3, CD15, CD34, CD68, and MAC 387 were used in a second tier of analysis. The results were evaluated in a step-wise fashion. All B cell lymphomas and the majority of T cell cases were identified correctly by their reactivity for CD20 and CD45RO, respectively. Using the five standard lymphomas markers, 12 of 19 cases of GS had a phenotype that would be relatively unusual in non-Hodgkin's lymphoma—as reflected by CD43 and MB2 coexpression without CD20 or CD45RO-whereas 7 cases of GS showed a "CD43-only" phenotype and were there fore considered possible T cell lesions. All 19 GS cases were labeled by at least one second-tier marker and 18 exhibited two or more of these determinants at that level of evaluation. All T cell lymphomas failed to express CD 15, CD34, CD68, or MAC 387; however, 3 of 20 B cell tumors were focally positive for CD 15. CD3 labeled 9 of 11 cases of T cell lymphoma but also was seen in 11 of 16 cases of GS. These results indicate that, in suspected lymphoma cases, CD45-positivity, but failure to express CD20 or CD45RO, suggests the possibility of GS. Additional immunohistologic studies, in particular those for lysozyme or myeloperoxidase, can then be used to further define the tumoral lineage. Int J Surg Pathol 2(3):177-186, 1995

p63 expression in Merkel cell carcinoma predicts poorer survival yet may have limited clinical utility

OBJECTIVES

To determine the clinical utility of p63 expression, which has been identified in several cohorts as a predictor of poorer prognosis in Merkel cell carcinoma (MCC).

METHODS

Immunohistochemistry was used to determine p63 expression on MCC tumors from 128 patients.

RESULTS

Of the patients, 33% had detectable p63 expression. p63 Positivity was associated with an increased risk of death from MCC (hazard ratio, 2.05; P = .02) in a multivariate Cox regression model considering stage at presentation, age at diagnosis, and sex. Although p63 expression correlated with diminished survival in this largest cohort reported thus far, the effect was weaker than that observed in prior studies. Indeed, within a given stage, p63 status did not predict survival in a clinically or statistically significant manner.

CONCLUSIONS

It remains unclear whether this test should be integrated into routine MCC patient management.

Cutaneous angiosarcoma clinically presenting as progressive solid facial edema in a 43-year-old male

Cutaneous angiosarcoma of the head and neck is a rare, highly malignant neoplasm; prognosis is heavily influenced by tumor size, resectability, and stage at initial diagnosis. Most patients present with one to several erythematous to violaceous patches, plaques, or nodules. However, the clinical presentation is highly variable and leads to delayed diagnosis. We report cutaneous angiosarcoma in a 43-year-old man who presented with an 11-month history of progressive solid (non-pitting) edema involving his entire face, scalp, eyelids, and neck without characteristic clinical features of cutaneous angiosarcoma. A skin biopsy had shown non-specific findings consistent with solid facial edema or rosacea. Various etiologies were considered but there was no significant improvement after directed medical therapy. Repeat skin biopsies revealed angiosarcoma involving the dermis and sub-cutis. Computed tomography (CT) of the chest showed multiple lung nodules bilaterally and a lytic lesion in the T6 vertebra consistent with metastases. He was treated with single agent chemotherapy (paclitaxel), and had a partial response that restored his ability to open both eyes spontaneously; However, his edema has recently progressed 7 months after diagnosis. This is a rare example of cutaneous angiosarcoma presenting as progressive solid facial edema, which underscores the diverse range of clinical manifestations associated with this neoplasm.

Analysis of Tp53 codon 72 polymorphisms, Tp53 mutations, and HPV infection in cutaneous squamous cell carcinomas

Background

Non-melanoma skin cancers are one of the most common human malignancies accounting for 2–3% of tumors in the US and represent a significant health burden. Epidemiology studies have implicated Tp53 mutations triggered by UV exposure, and human papilloma virus (HPV) infection to be significant causes of non-melanoma skin cancer. However, the relationship between Tp53 and cutaneous HPV infection is not well understood in skin cancers. In this study we assessed the association of HPV infection and Tp53 polymorphisms and mutations in lesional specimens with squamous cell carcinomas.

Methods

We studied 55 cases of histologically confirmed cutaneous squamous cell carcinoma and 41 controls for the presence of HPV infection and Tp53 genotype (mutations and polymorphism).

Results

We found an increased number of Tp53 mutations in the squamous cell carcinoma samples compared with perilesional or control samples. There was increased frequency of homozygous Tp53-72R polymorphism in cases with squamous cell carcinomas, while the Tp53-72P allele (Tp53-72R/P and Tp53-72P/P) was more frequent in normal control samples. Carcinoma samples positive for HPV showed a decreased frequency of Tp53 mutations compared to those without HPV infection. In addition, carcinoma samples with a Tp53-72P allele showed an increased incidence of Tp53 mutations in comparison carcinomas samples homozygous for Tp53-72R.

Conclusions

These studies suggest there are two separate pathways (HPV infection and Tp53 mutation) leading to cutaneous squamous cell carcinomas stratified by the Tp53 codon-72 polymorphism. The presence of a Tp53-72P allele is protective against cutaneous squamous cell carcinoma, and carcinoma specimens with Tp53-72P are more likely to have Tp53 mutations. In contrast Tp53-72R is a significant risk factor for cutaneous squamous cell carcinoma and is frequently associated with HPV infection instead of Tp53 mutations. Heterozygosity for Tp53-72R/P is protective against squamous cell carcinomas, possibly reflecting a requirement for both HPV infection and Tp53 mutations.

Keratinocyte dysplasia in hematopoietic stem cell transplantation recipients in the day-28-to-84 posttransplantation period

Severe keratinocyte dysplasia (SKD) has been reported as a common event in the early posttransplantation period of hematopoietic stem cell transplantation patients. The purpose of our study is to determine the possible causes of SKD during the intermediate posttransplantation period and to ascertain its prevalence in skin biopsies. Skin biopsy slides, obtained from hematopoietic stem cell transplantation recipients who were days 28 to 84 posttransplantation, were evaluated for SKD. Forty-four examples of SKD were identified in 467 slides, or 9%. Thirty-seven patients were evaluated as cases in a case-control design. SKD was strongly associated with a conditioning regimen containing busulfan with an odds ratio of 7.25 (P = .0002). In a multivariate-adjusted analysis, SKD was not associated with cyclophosphamide, fludarabine, total-body irradiation, or a nonmyeloablative conditioning regimen. SKD was not associated with clinical acute graft-versus-host disease. SKD histology gradually resolved, reaching a normal histology after an average of 241 days. This study finds that severe keratinocyte dysplasia in the period 28 to 84 days post-HSCT is strongly associated with a busulfan-conditioning regimen.

Agminated cellular neurothekeoma

Cellular neurothekeoma represents a benign, slow-growing neoplasm that typically occurs as a solitary lesion on the face, neck or arm. Reports of multiple lesions are rare. To our knowledge, multiple lesions occurring as eruptive clusters localized to a single anatomical site has not been previously reported. This report details a case of an agminated cellular neurothekeoma occurring on the nose of a 28-year-old man. Recognition of multiple localized eruptive lesions of cellular neurothekeoma is important in order to facilitate correct diagnosis and avoid unnecessary treatment.

Transcriptome-wide studies of merkel cell carcinoma and validation of intratumoral CD8+ lymphocyte invasion as an independent predictor of survival

PURPOSE

Merkel cell carcinoma (MCC) is a polyomavirus-associated skin cancer that is frequently lethal and lacks established prognostic biomarkers. This study sought to identify biomarkers that improve prognostic accuracy and provide insight into MCC biology.

PATIENTS AND METHODS

Gene expression profiles of 35 MCC tumors were clustered based on prognosis. The cluster of genes overexpressed in good-prognosis tumors was tested for biologic process enrichment. Relevant mRNA expression differences were confirmed by quantitative polymerase chain reaction and immunohistochemistry. An independent set of 146 nonoverlapping MCC tumors (median follow-up, 25 months among 116 living patients) was employed for biomarker validation. Univariate and multivariate Cox regression analyses were performed.

RESULTS

Immune response gene signatures were prominent in patients with good prognoses. In particular, genes associated with cytotoxic CD8+ lymphocytes were overexpressed in tumors from patients with favorable prognoses. In the independent validation set, cases with robust intratumoral CD8+ lymphocyte infiltration had improved outcomes (100% MCC-specific survival, n = 26) compared with instances characterized by sparse infiltration (60% survival, n = 120). Only stage and intratumoral CD8 infiltration (but not age, sex, or CD8+ lymphocytes localized to the tumor-stroma interface) were significant in both univariate and multivariate Cox regression analyses. Notably, traditional histologic identification of tumor-infiltrating lymphocytes was not a significant independent predictor of survival.

CONCLUSION

Intratumoral CD8+ lymphocyte infiltration can be readily assessed on paraffin-embedded tissue, is independently associated with improved MCC-specific survival, and therefore, may provide prognostic information that enhances established MCC staging protocols.

An infiltrative variant of non-neural granular cell tumor: a case report

Dermal non-neural granular cell tumors are rare tumors of indeterminate lineage that typically present as well-circumscribed tumors with nuclear pleomorphism and mitotic activity. We describe a dermal non-neural granular cell tumor with a distinctive growth pattern with granular cells interspersed between collagen bundles. This asymptomatic papule arose on the scapula of a 46-year-old woman and consisted of a mixture of epithelioid and spindled granular cells. The immunohistochemical characteristics were similar to those of previously reported dermal non-neural granular cell tumors. Despite mild nuclear pleomorphism and dispersion of lesional cells among collagen bundles, mitoses were not present and Ki-67 staining indicated a low proliferative rate. In addition to being S-100 protein negative and NKI/C3 positive, our case was positive for PGP9.5 and weakly positive for neuron-specific enolase, a staining pattern similar to what has been observed for cellular neurothekeomas. Our case could represent a dermal non-neural granular cell tumor with unique architecture, a granular cellular neurothekeoma or a granular cell dermatofibroma. As both dermal non-neural granular cell tumor and cellular neurothekeoma are of indeterminate lineage, our case with features characteristic of both entities may suggest a common precursor or lineage for dermal non-neural granular cell tumor and cellular neurothekeoma.

S100, HMB-45, and Melan-A negative primary melanoma

The diagnosis of malignant melanoma can be challenging given the wide variation in morphologic features and immunohistochemical stains are often used to confirm the diagnosis. We report a case of melanoma with loss of staining for S100 protein, HMB-45, and Melan-A, with retained expression of tyrosinase. Regional lymph node metastases showed positive S100 protein staining. Although the loss of phenotypic markers including S100 protein has been reported in metastatic melanoma, loss of S100 in primary melanoma is rare. Discordant staining between primary and metastatic lesions further emphasizes the protean nature of melanoma.

Atypical neurofibroma of the skin and subcutaneous tissue: clinicopathologic analysis of 11 cases

BACKGROUND

Neurofibroma (NF) is a relatively common cutaneous tumor, which typically presents little diagnostic difficulty. Occasionally, however, pleomorphic cells may be present in NF raising consideration of other neoplasms like malignant peripheral nerve sheath tumor (MPNST).

METHODS

This study examines the clinicopathologic and immunohistochemical features of 11 dermal and subcutaneous 'atypical' NF.

RESULTS

9/11 (82%) atypical NF were from females, aged 8-70 years. One patient had neurofibromatosis-1. Most presented on the extremities or trunk. The atypical cells had large hyperchromatic, irregular nuclei, and were arranged in a distinct lamellar or fibrillar pattern. Some tumors were hypercellular, but marked density characteristic of MPNST was not observed. All were nonplexiform. Mitoses were mostly absent. The pleomorphic cells expressed S-100 protein. All were negative for p53. MIB-1 was negative in 7/10 (70%) and stained only rare cells in 3 (30%). Epithelial membrane antigen (EMA) and p16 expression were variable. Of six patients with available follow-up, no tumor recurred and none developed malignancy (range 6-63, mean 33 months).

CONCLUSIONS

Superficial atypical NF, while morphologically unusual, has no apparent association with neurofibromatosis-1 or short-term risk of recurrence or malignant transformation. Awareness of this variant is important in order to avoid misdiagnosis of a more aggressive neoplasm.

Collagen-rich variant of benign epithelioid peripheral nerve sheath tumor of the skin

Schwannoma and neurofibroma account for the majority of cutaneous benign peripheral nerve sheath tumors and usually pose little diagnostic difficulty in their classic forms. In rare instances, however, benign peripheral nerve sheath tumors may display epithelioid morphology and lack otherwise usual features of schwannoma or neurofibroma, making classification difficult. These unusual changes may prompt consideration of other benign neoplasms or a malignancy. Benign epithelioid peripheral nerve sheath tumor (BEPNST) is a somewhat non-specific term recently proposed to describe these neoplasms of imprecise histogenesis. Also diagnostically challenging, rare BEPNST with unusual arrangements of extracellular collagen have been described and reported as neuroblastoma-like schwannoma and collagenous spherulosis. We report a unique case of cutaneous BEPNST with a peculiar arrangement of abundant extracellular collagen, different than the previously observed patterns. Specifically, the neoplastic cells in this tumor were nearly obscured by the collagen, which formed large nodules and compressed the majority of the few remaining tumor cells to the periphery of the lesion. This excessive collagen production emphasizes the importance of adequate sampling to ensure a correct diagnosis.

Lymphomatoid papulosis with CD1a+ dendritic cell hyperplasia, mimicking Langerhans cell histiocytosis

Although CD1a+ dendritic cells (DC) in cutaneous T-cell lymphomas (CTCL) have been well documented, the presence of large numbers of DC within lymphoid infiltrates can pose a diagnostic difficulty. We present a case of a 70-year-old man with a 3-year history of recurrent red papules and plaques on the extremities and trunk that was referred to our institution, with the diagnosis of Langerhans cell histiocytosis. Skin biopsies showed a wedge-shaped cellular infiltrate in the superficial and deep dermis consisting of two cell populations. Most prominent were clusters of epithelioid cells with grooved nuclei and abundant eosinophilic cytoplasm, which stained with antibodies to CD1a and S-100. A second, less prominent population of atypical lymphocytes, some with enlarged, hyperchromatic and convoluted nuclei, were intermixed. The latter were positive for CD30, CD3 and CD5 and negative for CD20, CD34, CD68, ALK-1 and TdT. T-cell receptor gene rearrangement studies confirmed a clonal T-cell population, which with the clinical history was consistent with the diagnosis of lymphomatoid papulosis. While previous studies have shown an increased density of dermal DC in CTCL, we believe that this represents the first report of an unusually florid DC proliferation mimicking Langerhans cell histiocytosis and masking a lymphoproliferative disorder.

Giant cell rich histiocytic dermatitis/panniculitis associated with thrombocytosis

An unusual histiocytic dermatitis associated with a lymphoplasmacytic and histiocytic panniculitis appears to represent a previously undescribed disease process. A 56-year-old woman presented with a 5 year history of a violaceous, maculo-papular rash primarily on her legs. It began approximately 8 months before therapy for thrombocytosis. The rash subsequently progressed to form confluent patches and plaques on her torso and arms. The clinical impression was of disseminated granuloma annulare, but multiple biopsies from different sites did not confirm this. Histologic examination revealed a diffuse proliferation of histiocytic cells in the dermis, without well-formed granulomas or necrobiosis. The cells had large, focally irregular nuclei with prominent nucleoli, and were associated with scattered, often bizarre multinucleate giant cells. Immunohistochemistry demonstrated the histiocytic cells to be positive for S100 and CD68 and negative for CD1a. Perivascular siderophages as well as a lymphoplasmacytic and histiocytic panniculitis accompanied the process. The striking cutaneous changes are of unknown etiology but appear to be previously undescribed.

Eccrine angiomatous hamartoma with elements of an arterio-venous malformation: a newly recognized variant

We present the case of a 54-year-old man with a brown-red nodule on the hand that had been present since early adulthood. Histology of the excisional biopsy revealed hyperplasia and proliferation of eccrine, apocrine, lipomatous, and vascular structures. These findings were most characteristic of the entity known as eccrine angiomatous hamartoma (EAH), an uncommon tumor that may present variable clinical and histological features. In addition, this particular case exhibited a prominent component of arterio-venous malformation that distinguishes it from other EAHs described in the literature and adds to the spectrum of histologic findings that can be seen with this entity.

Acute lymphoblastic leukemia presenting with urticarial plaques and hypereosinophilia in a child

Our report describes a previously healthy 10-year-old female who was seen for urticarial plaques and mild loss of appetite. An initial laboratory workup revealed an elevated leukocyte count of 30,000/microL and a peripheral eosinophil count of 22,500/microL. A skin biopsy showed a marked hypersensitivity tissue response with abundant eosinophils. Further investigation of her peripheral eosinophilia uncovered Giardia lamblia in a stool sample. Despite treatment with the anti-parasitic agent furazolidone, the patient's urticarial plaques, leukocyte count, and peripheral eosinophil count remained unchanged. A bone marrow biopsy confirmed a diagnosis of acute lymphoblastic leukemia (ALL). ALL with hypereosinophilia (ALL/Eo) represents a rare and distinct subset of ALL, with more than 30 cases documented in the literature. Our discussion summarizes the clinical aspects of this disease and reviews the reported dermatological manifestations of ALL/Eo.

Congenital panfollicular nevus: report of a new entity

The various forms of non-melanocytic nevi (hamartomas) are usually encountered in pediatric patients, and nevus sebaceous of Jadassohn is the most common to have undifferentiated pilosebaceous units. We report a unique congenital follicular nevus that fails to meet the criteria of any previously described follicular neoplasm, despite the plethora of alternatives. Clinically considered a syringocystadenoma papilliferum, the excised lesion contained multiple dermal nodules that exhibited nearly all stages of follicular differentiation. The periodicity of the follicular proliferations was akin to normal terminal hair, and a prominent perifollicular sheath surrounded each. This benign lesion of abortive hair follicles was unassociated with any established genodermatous syndrome or other adnexal neoplasm.

Cytokeratin 5/6 Immunostaining in Cutaneous Adnexal Neoplasms and Metastatic Adenocarcinoma

The differentiation of primary cutaneous adnexal neoplasms (CANs) from dermal-based metastatic lesions can be difficult. Cytokeratin 5/6 (CK 5/6) has a relatively limited expression profile, being relatively specific for mesothelium and other "pavement" type epithelium such as squamous epithelium. To date, the degree and distribution of CK 5/6 expression in cutaneous neoplasms has not been extensively studied. We speculate that since most of CANs arise from similar epithelium, they should express CK 5/6 and, therefore, CK 5/6 could potentially be helpful in distinguishing these lesions from most of metastatic neoplasms, which usually do not express this marker. Formalin-fixed, paraffin-embedded tissue sections from 228 previously classified CANs and 27 metastatic adenocarcinomas (17 breast, 4 colon, 2 prostate, 2 ovary, 1 lung, and 1 esophagus) were immunostained with anti-CK 5/6. Anti-CK 5/6 labeled 2 of 2 proliferating trichilemmal tumors, 6 of 6 poromas, 4 of 5 hydrocystomas, 10 of 10 cylindromas, 10 of 10 eccrine acrospiromas, 8 of 10 pilomatricoma, 10 of 10 nevus sebaceus, 9 of 9 desmoplastic trichoepitheliomas, 7 of 7 nevus sebaceus with basal cell carcinomas, 10 of 10 pilar cysts, 14 of 14 trichilemmomas, 10 of 10 syringomas, 6 of 7 chondroid syringomas, 10 of 10 hidradenoma papilliferum, 9 of 9 sebaceus adenomas, 3 of 3 microcystic adnexal carcinomas, 10 of 10 eccrine spiradenomas, 4 of 4 syringocystadenoma papilliferum, 3 of 5 ocular sebaceous carcinomas, 28 of 28 basal cell carcinomas, 16 of 16 trichoepitheliomas, and 33 of 33 trichoepitheliomas with basal cell features. By contrast, 9 of 27 metastatic adenocarcinomas stained positively, although only two of these stained strongly. Cumulatively, CK 5/6 was expressed by most (97%) of CANs, while only 33% of metastatic adenocarcinomas showed positive expression. The sensitivity of this marker in the malignant lesions (other than basal cell carcinoma) is 78%, while the specificity is 67%. If all lesions are considered, the sensitivity increases to 97%. Therefore, CK 5/6 may prove to be a useful adjunct marker in distinguishing CANs from metastatic lesions.

Are en face frozen sections accurate for diagnosing margin status in melanocytic lesions?

To assess the diagnostic accuracy of margin evaluation of melanocytic lesions using en face frozen sections compared with standard paraffin-embedded sections, we studied 2 sets of lesions in which en face frozen sections were used for analysis of surgical margins (13 from malignant melanomas [MMs] and 10 from nonmelanocytic lesions [NMLs]). Routine permanent sections were cut after routine processing. The slides were mixed and coded randomly. Fifteen dermatopathologists examined the cases separately. Margin status was categorized as positive, negative, or indeterminate. Kappa statistics were calculated per dermatopathologist and per case. One case from each group was excluded because epidermis was not available in the routine sections. Of 330 evaluations (22 cases, 15 dermatopathologists), there were 132 diagnostic discrepancies (40.0%): 66 each for MM and NML (mean per case for both diagnoses, 6). In 9 instances (6.8%), the change was from positive (frozen) to negative (permanent) and in 43 (32.6%), from negative (frozen) to positive (permanent). There was poor agreement between frozen and permanent sections (kappa range per dermatopathologist, -0.1282 to 0.6615). If permanent histology is considered the "gold standard" for histologic evaluation, en face frozen sections are not suitable for accurate surgical margin assessment of melanocytic lesions.

Atypical Spitz nevi/tumors: lack of consensus for diagnosis, discrimination from melanoma, and prediction of outcome

The biological nature of Spitz nevi/tumors and their diagnostic distinction from, or relationship to, melanoma remain unresolved issues. In this report, a series of 30 melanocytic lesions removed from 28 patients, including atypical Spitz nevi/tumors and metastasizing Spitzoid tumors/melanomas, were evaluated by a panel of dermatopathologists to evaluate interobserver diagnostic concordance and to assess the prognostic power of histological criteria. For inclusion in the study, each lesion had to display some criteria for the Spitz nevus, and in addition one of the following was required: (1) definitive clinical outcome such as metastasis or death of disease, or (2) long-term follow-up if the patient remained disease free. Each lesion was reviewed independently and blinded as to the clinical data by 10 pathologists, who categorized them as (1) typical Spitz nevus/tumor, (2) atypical Spitz nevus/tumor, (3) melanoma, (4) tumor with unknown biological potential, or (5) other melanocytic lesion. There was limited discussion of criteria before the review. Evaluation of 17 Spitzoid lesions yielded no clear consensus as to diagnosis; in only one case did six or more pathologists agree on a single category, regardless of clinical outcome. Notably, however, some lesions that proved fatal were categorized by most observers as either Spitz nevi or atypical Spitz tumors. Conversely, seven or more pathologists scored 13 lesions as melanoma. These results illustrate (1) substantial diagnostic difficulties posed by many Spitz tumors, especially those with atypical features, even among experts, and (2) the lack of objective criteria for their distinction from melanoma and for gauging their malignant potential. Nevertheless, our observations do suggest that a biological relationship exists between the Spitz nevus/tumor and melanoma.

Cutaneous parachordoma. A light microscopic and immunohistochemical report of two cases and review of the literature

Parachordomas are rare cutaneous tumors that show virtually identical histologic findings to chordomas. Therefore, the major differential diagnosis in a case of parchordoma is metastatic chordoma. Parachordomas are benign neoplasms and most often develop on the extremities adjacent to tendons, synovium or osseous structures, as opposed to chordomas, which are malignant tumors located along the craniospinal axis. While recurrences may occur in cases of parachordoma, metastases have not been reported. In this report, two cases of parachordomas are reported and the literature reviewed. By light microscopy, parachordomas show eosinophilic bands of fibrous tissue separating lobules of cells with variably vacuolated cytoplasm (physaliphorous cells) admixed with more epithelioid cells in a myxoid stroma. Parachordomas and chordomas share immunohistochemical and ultrastructural features. Both stain with S-100 protein and vimentin, and ultrastructurally both demonstrate cytoplasmic vacuoles, intermediate filaments, pinocytotic vesicles, celljunctions, and cytoplasmic membranes with microvillous processes. Chordomas more frequently express cytokeratin (98% vs. 66% in parachordomas) and epithelial membrane antigen (90% vs. 20% in parachordomas) and chordomas have a larger number of rough endoplasmic reticulum-mitochondrial complexes. Thus, positive staining with epithelial membrane antigen and the identification of a large number of rough endoplasmic reticulum-mitochondrial complexes are suggestive of metastatic chordoma. However, the definitive distinction remains a clinical one after appropriate radiologic studies of the skull and spinal chord.

A new application of BCG antibody for rapid screening of various tissue microorganisms

BACKGROUND

In routine dermatopathology there is growing demand for a simple, fast, cost-effective, and highly sensitive screening tool for the detection of microorganisms.

OBJECTIVE

Our purpose was to determine whether immunostaining with polyclonal anti-Mycobacterium bovis (BCG), which is known for its interspecies cross-reactivity, is a suitable screening method for many common microorganisms in dermatopathologic specimens.

METHODS

A total of 254 formalin-fixed, paraffin-embedded skin specimens of viral, protozoal, fungal, and bacterial infections were stained with appropriate histochemical stains and with anti-BCG.

RESULTS

Anti-BCG labeled bacteria and fungi with high sensitivity and minimal background staining, but did not react with spirochetes, viruses, or protozoa (Leishmania). The quality and sensitivity of anti-BCG staining were superior to conventional histochemical stains.

CONCLUSION

Because of its cross-reactivity with many bacteria and fungi as well as its high sensitivity and minimal background staining, the anti-BCG immunostain is a promising screening tool for the detection of the most common bacterial and fungal microorganisms in paraffin-embedded skin specimens.

Dermoscopy (epiluminescence microscopy) of pigmented skin lesions. Current status and evolving trends

Dermoscopy (epiluminescence microscopy) is a noninvasive technique that is designed for in vivo microscopic examination of pigmented skin lesions, particularly for the early recognition of malignant melanoma. Since its introduction, dermoscopy technique has undergone extensive improvements; the instruments have become more readily available; and the diagnostic indications, benefits, and limitations have been better delineated. This article offers a concise review of the technique of dermoscopy, assesses the current status, and makes some predictions for future applications.

CD44 expression in benign and malignant nevomelanocytic lesions

CD44 is an integral membrane glycoprotein that is a principal receptor for hyaluronan and plays a role in cell-extracellular matrix interactions. Recent studies of melanomas in mouse models have suggested that increased CD44 expression by these tumors may relate to metastatic potential. Immunohistochemical expression of CD44 (standard [s] and variant [v6]) in benign and malignant nevomelanocytic lesions was assessed in formalin-fixed, paraffin-embedded tissue and was correlated with histological parameters and prognostic factors. Cases included benign nevi (three junctional, four compound, five intradermal, five blue, six Spitz, one deep penetrating), architecturally disordered (dysplastic) nevi (three, and primary (22) and metastatic melanomas (eight). All of the benign lesions showed diffuse and essentially uniform membrane staining of CD44s in nevomelanocytic cells, regardless of lesion size, depth, or extent of dermal involvement. In contrast, semiquantitative analysis (0 to 3+) of the primary melanomas showed heterogeneous and decreased staining of CD44s, which inversely correlated with lesion size (-0.569) and depth of invasion (-0.622 and -0.617 for Breslow's depth and Clark's level, respectively). These results were significant at P < .05. CD44s expression in metastases paralleled that of their respective primaries. None of the benign nevomelanocytic lesions showed CD44v6 staining. In contrast, all of the malignant nevomelanocytic lesions showed cytoplasmic staining of the tumor cells. Pretreatment with chondroitinase did not alter CD44s staining. CD44s expression by immunohistochemical determination is uniform in benign nevomelanocytic lesions. Malignant melanomas show decreased, heterogeneous staining that inversely correlates with increasing size, depth, and level of invasion. CD44 expression may be a prognostic indicator in malignant melanomas. Tumor staining with anti-chondroitin sulfate monoclonal antibodies suggests that CD44s may be expressed as a chondroitin sulfate proteoglycan in primary melanomas.

Expression of nerve growth factor and epidermal growth factor receptors in neural nevi with nevic corpuscles

The histogenesis of "nevic corpuscles" (NCs) in neural nevi is still controversial. Recent studies have revealed that nerve growth factors (NGFs) and other growth factors [that is, epidermal growth factor (EGF)] could have various paracrine and autocrine functions on Schwann cells and melanocytes. We examined the immunohistochemical expression of NGF and EGF receptors (r) in 15 cases of neural nevi containing NCs along with 37 cases of other benign and malignant melanocytic lesions without neural differentiation (total, 52). Section were prepared from formalin-fixed and paraffin-embedded tissues. Monoclonal antibodies to NGFr and EGFr were used with the Avidin-biotin-complex (ABC) technique. We found strong reactivity for NGFr in 14 of 15 neural nevi with a predilection for NCs, but only eight of 37 were positive in the other group of melanocytic lesions without neural differentiation (four Spitz nevi, two melanomas, and two compound nevi). EGFr expression was limited mainly to NCs in four cases of neural nevi. We conclude that neural differentiation and NC formation are associated with NGFr overexpression, whereas EGFr expression is only limited. The relative paucity of NGFr expression in other type of benign and malignant melanocytic lesions supports the view that neural "differentiation" is a distinct process in certain long-standing melanocytic nevi. We postulate that NGFr overexpression may be the result of the reactivation of oncofetal genes that could become manifest in either abnormal schwannian differentiation (as seen in neural nevi), in a neoplastic context (as seen in neural and melanocytic tumors).

Cutaneous neural heterotopias and related tumors relevant for the dermatopathologist

Heterotopic neural tumors are rare in the skin; however, when encountered, they often pose a diagnostic problem. While the clinicopathologic features of most neuroaxis abnormalities are well-documented in the neuropathologic literature, their significance in cutaneous pathology as well as the associated nonneural dermatopathologic findings have not received enough attention. This report offers a comprehensive review of the most common cutaneous neural heterotopic abnormalities and their related tumors. The clinicopathologic features of the following entities along with their histogenetic considerations are discussed: classical and rudimentary meningocele, primary cutaneous meningioma, heterotopic brain tissue (nasal glioma), peripheral primitive neuroectodermal tumor, metastatic neuroblastoma, and ganglioneuroma. Familiarity with the associated dermatopathologic changes and with the differential diagnosis should assist in arriving at the correct diagnosis even without special training in dermatopathology or neuropathology.

Trisomy 7 in keratoacanthoma and squamous cell carcinoma detected by fluorescence in-situ hybridization

Keratoacanthoma (KA) is generally considered to be a clinically and histologically distinct entity, but it often remains difficult to separate from well-differentiated squamous cell carcinoma (WDSCC). Recently, trisomy 7 has been identified in squamous cell carcinoma of the skin. In this study, we examined classical KA (n = 6), WDSCC (n = 7) and squamous cell carcinoma with KA-like features (SCC-KA) (n = 8) for trisomy 7 by fluorescence in-situ hybridization (FISH) to determine if this chromosomal abnormality is unique to squamous lesions diagnosed as WDSCC, or shared by both KA and SCC. In addition, the pertinent clinical-histopathologic findings were summarized. Trisomy 7 was identified in one KA, one SCC-KA and two WDSCC. This study demonstrates that there is a chromosomal abnormality shared by KA and SCC, providing further evidence that KA is most likely a form of SCC. Further studies are required to determine if trisomy 7 in these lesions is of prognostic significance.

Keratoacanthoma versus squamous cell carcinoma. An immunohistochemical reappraisal of p53 protein and proliferating cell nuclear antigen expression in keratoacanthoma-like tumors

The controversy of distinguishing keratoacanthomas (KAs) from well-differentiated squamous cell carcinomas (WDSCCs) is well established. A number of recent studies have attempted to separate these processes with the use of immunohistochemical stains. In corroboration, we have retrospectively reviewed three groups of patients with tissue biopsies with features of classical KA (n = 7), WDSCC (n = 8), and squamous cell carcinoma with KA-like features (SCC-KA) (n = 9). We compared their clinical and histological differences as well as their immunohistochemical differences using antibodies to proliferating cell nuclear antigen (PCNA), and wild- and mutant-type p53 protein. Classical KA showed a PCNA staining pattern located predominantly around the basal cell layers, in contrast to a relatively diffuse staining pattern seen in WDSCC. SCC-KA showed considerable overlap with these two types of staining patterns. The p53 staining showed basal, patchy, or diffuse patterns. These patterns were present in all three groups. Although both PCNA and p53 expression was more often present in SCC-KA, there were no statistical differences among the groups. In conclusion, the overlapping expression patterns of PCNA and p53 in keratocanthoma-like tumors support the hypothesis that these tumors represent a possible biologic spectrum. Because of the absence of significant statistical differences in the expression of these antigens, PCNA and p53 have not proved to be helpful in differentiating KA from KA-like squamous cell carcinoma.

CD31 immunoreactivity in mesenchymal neoplasms of the skin and subcutis: report of 145 cases and review of putative immunohistologic markers of endothelial differentiation

CD31 has recently been reported as a specific marker of endothelial differentiation among non-hematopoietic human neoplasms. In order to address this contention in particular regard to tumors of the skin and subcutis, the authors undertook a comparative study that surveyed 145 mesenchymal lesions. The antibodies used were directed against CD31 (clone JC/70A) and CD34 (clone My10), and these were compared with binding of Ulex europaeus I agglutinin (UEA). Proliferations that were included in the category of vascular tumors included cavernous and capillary hemangiomas (17 cases); lymphangiomas (8); epithelioid ("histiocytoid") hemangiomas (3), papillary endovascular hemangioendothelioma (1), angiosarcoma (7), and Kaposi's sarcoma of the mixed angiomatoid and spindle-cell type (17). CD31-immunoreactivity was observed in 35 of 53 vascular lesions; the neoplastic cells in a single angiosarcoma and the spindle cells in each case of Kaposi's sarcoma (KS) were not labeled. In all of the latter tumors, however, staining for CD31 was identified in the endothelia of angiomatoid areas and non-neoplastic blood vessels. These results compared favorably with those seen with anti-CD34, which decorated 36 of 53 vascular tumors--including 8 of 17 KS cases--and UEA, which bound to the neoplastic cells of 36 lesions. In contrast, all of 92 non-endothelial tumors included in this study (34 nerve sheath tumors [30 benign; 4 malignant]; 39 fibrohistiocytic neoplasms [11 benign; 28 malignant]; 9 smooth muscle tumors [6 benign; 3 malignant]; 7 glomus tumors; and 3 giant cell fibroblastomas) were negative for CD31. UEA labeled 3 non-vascular neoplasms, whereas 38 lesions of that type were CD34-positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural spectrum of cutaneous nerve sheath myxoma/cellular neurothekeoma

The histogenesis of cutaneous nerve sheath myxoma (NSM)/cellular neurothekeoma (CNT) is still controversial. In this study, we examined the ultrastructural features of 16 NSM (3 classical, 11 CNT, and 2 mixed NSM/CNT). We classified the cells into 4 groups ultrastructurally. Type I cells were undifferentiated polygonal cells with ovoid nuclei, cytoplasmic microfilaments, and occassionally with microfilament-associated dense bodies. In most cells, the cytoplasmic membrane showed focal membranous densities and occasional basal-lamina-like material. This cell type comprised approximately 90% of CNT. Type II cells were more differentiated, had ovoid or spindled shapes, were rich in intracytoplasmic filaments, and were surrounded by continuous basal lamina. These cells were consistent with Schwann cells and were present in the classical and mixed forms of NSM, and in a single case of CNT. Type III cells had features of perineurial cells and were relatively rare in classical NSM. Type IV cells resembled fibroblasts and were encountered in all variants of NSM. These results support the view that 1) the classical NSM has neural (mainly Schwann cell) differentiation, 2) CNT is predominantly composed of undifferentiated cells with partial features of Schwann cells, smooth muscle cells, myofibroblasts and fibroblasts, suggesting a divergent differentiation, and 3) CNT and NSM represent a histologic spectrum, but in CNT, the neural features are not fully expressed.

Histiocytosis X of the vulva with a confusing clinical and pathologic presentation. A case report

Histiocytosis X (HX) is a rare disorder of Langerhans cells and most commonly occurs in children. We report a case of HX of the vulva in a 76-year-old woman that clinically simulated a yeast infection of the vulva but histologically resembled an amelanotic melanoma. We briefly report the clinical and pathologic features of this case, which responded to vincristine followed by vinblastine and was in complete remission after nine months.

Primary cutaneous meningioma associated with von Recklinghausen's disease

Cutaneous meningeal tumors are rare and can pose a diagnostic problem. We present a case of a 12-year-old girl with a family history of von Recklinghausen's disease. The patient was asymptomatic until the age of 11, when she developed two lesions on the head, both diagnosed as plexiform neurofibroma. Subsequently, she presented with a subcutaneous nodule on the left posterior occipital scalp which was excised. On histology, the tumor was composed of spindle-shaped cells with diffuse and nested patterns. A whorled configuration of the cells, with occasional giant cells and psammoma bodies, was present. There was no evidence of connection between the tumor and the underlying tissues. Immunohistochemical studies were positive for epithelial membrane antigen, vimentin, and weakly for neuron-specific enolase. Cytokeratin, S-100 protein, and muscle markers were negative. Based on these features, the diagnosis of cutaneous meningioma was made. An MRI examination failed to detect any communication between the tumor site and the meninges; however, asymptomatic bilateral acoustic neuromas were identified. This case, besides being of interest as a primary cutaneous meningioma, also documents a unique combination of findings, i.e., plexiform neurofibroma, meningioma, and cerebellopontine acoustic neuromas, which should alert the clinician to a forme fruste presentation of von Recklinghausen's disease.

S-100 protein-negative malignant melanoma: fact or fiction? A light-microscopic and immunohistochemical study

S-100 protein is considered a characteristic immunohistochemical marker for all nevomelanocytic lesions, in which it is expected to be present consistently. We reviewed 17 cases of malignant melanomas that previously tested negative for S-100 protein. They were reevaluated by light microscopy, a broad panel of immunohistochemical reagents including monoclonal and polyclonal antibodies to S-100 protein, and electron microscopy. On reexamination, five of the 17 cases were reclassified as non-melanoma tumors, and eight of the 17 cases were found to be positive for S-100 protein (six with monoclonal and eight with polyclonal antibodies) and HMB-45 antigen, consistent with melanoma. The remaining four cases repeatedly tested negative for S-100 protein despite various antigen enhancement methods, but they were positive for HMB-45 antigen and contained premelanosomes or melanosome-like structures by electron microscopy. Two of these repeatedly S-100 negative melanomas were acrally located; although the numbers are small, a possible relationship to a specific anatomic location cannot be excluded. These findings suggest that in a small subset of melanomas S-100 protein is either not fully expressed or is below the level that can be detected by routine immunohistochemistry. We also conclude that in the majority of the initially S-100-negative cases of melanomas, the misdiagnosis may occur due to the use of an incomplete immunohistochemical panel, technical reasons, or the inherent variability of tissue expression of S-100 protein.

Hamartoma of the tongue in an infant with a primary diagnosis of ectrodactyly-ectodermal dysplasia-cleft lip and palate syndrome

We describe a case of an unusual tongue hamartoma associated with ectrodactyly-ectodermal dysplasia-clefting syndrome in a 3-month-old white female infant. The lesion was composed of a mixture of salivary glands, adipose tissue, smooth muscle and skeletal muscle in a haphazard fashion. Lingual hamartomas are rare and can present a clinical differential diagnostic problem. We review the literature on this unique combination of malformations.

Large-cell acanthoma of the skin. A study by image analysis cytometry and immunohistochemistry

Although large-cell acanthoma is a well-known clinicopathological entity, its biologic spectrum and nature are still subject to debate. We studied seven cases of large-cell acanthoma by image analysis cytometry for DNA content and by immunohistochemistry, using antibodies to proliferating cell nuclear antigen (PCNA)/cyclin. The data were compared with individual cases of seborrheic keratosis (SK), actinic keratosis (AK), and Bowen's disease (BD). The DNA distribution of large-cell acanthoma was variable. There were varying peaks at the DNA index values of 1 and 2 (diploid and tetraploid values), but all cases contained a significant aneuploid population between DNA index of 1 and 2. The mean DNA index was 1.44 (1.27-1.77); 1-20% of the cells exceeded 2, and 0-2% exceeded 3. The DNA index for lesions in the other differential diagnostic groups studied was as follows: SK, 1.0; AK, 1.4; BD, 1.8. The percentage of cells with positive nuclear staining for PCNA/cyclin was < 20% in all cases of large-cell acanthoma. The discrepancy between the high number of aneuploid and tetraploid cells observed on the DNA distribution curve and the lack of evidence for significant proliferation based on immunohistochemical stains suggest that these cells are resting cells with abnormal DNA clone. Although these results provide additional information about the biologic nature of large-cell acanthoma, they do not resolve the controversial nosologic status of lesions in this histologic group.

The preparation of frozen sections for micrographic surgery. A review of current methodology

BACKGROUND

Various methods are currently in use for preparing histological slides for micrographic surgery.

OBJECTIVE

Because many variables contribute to the quality preparation of frozen sections, a review of techniques available is useful to the Mohs surgeon. TECHNICAL METHODS AND RESULTS: Our techniques as well as the published work of others regarding mounting, embedding, freezing, slides, fixation, staining, and clearing are reviewed in detail. By the use of the options selected we were able to produce, in a short turn-around time, frozen sections with excellent quality and minimal artifact.

CONCLUSION

Presently all preparation techniques may introduce some degree of artifact. However, we feel the process described herein is adaptable to all Mohs surgery laboratories and will result in high quality specimens with minimal artifact.

Immunohistochemical study of Spitz nevi and malignant melanoma with use of antibody to proliferating cell nuclear antigen

Spitz nevi and malignant melanoma may be difficult to differentiate histologically. We applied an antibody to proliferating cell nuclear antigen (PCNA) to cases of Spitz nevi and malignant melanoma to determine if there were differences in reactivity. Cases were selected from the material of the Department of Pathology, University of Iowa Hospital. Formalin-fixed, paraffin-embedded cases were immunohistochemically stained with anti-PCNA (PC 10) with use of avidin-biotin complex technique. The cases were evaluated for the presence or absence of reactivity, staining intensity, and semiquantitative percentage of positive cells. Positive staining was observed in six of the 10 cases of Spitz nevi. The intensity of staining was weak and the number of positive cells varied from 10% to 40%. Positive staining was observed in all 10 cases of malignant melanoma. In eight of these 10 cases the intensity of staining was strong and the number of positive cells was greater than 40%. In the remaining two cases of melanoma, the intensity of staining was weak and the percentage of positive cells was 20-30%. These results indicate that PCNA staining may be observed in both Spitz nevi and malignant melanoma. Presence or absence of reactivity cannot be used in distinguishing these processes. However, a pattern of strong, diffuse reactivity may be used as an adjunct for supporting a diagnosis of melanoma.