Malignant melanoma of soft parts: an ultrastructural study of four cases

Clear cell sarcoma metastasizing to the pancreas

In this editorial based on a case report, we delve into a seldom-seen occurrence of clear cell sarcoma featuring pancreatic metastasis in a 47-year-old male patient. Recognized for its typical tendency to metastasize to the lungs, bones, and brain, clear cell sarcoma rarely extends its reach to the pancreas. Despite the initial absence of discernible abnormalities during the patient's physical examination, the manifestation of abdominal pain prompted further investigation. Subsequent abdominal computed tomography brought to light the presence of a pancreatic tumor, culminating in the definitive diagnosis of clear cell sarcoma with pancreatic metastasis. The successful management of this atypical presentation involved a series of surgical interventions, including distal pancreatectomy and splenectomy. This report not only sheds light on the infrequent manifestation of clear cell sarcoma within the pancreas but also underscores the pivotal role of vigilant postoperative follow-up in addressing this rare sarcoma. The emphasis on postoperative care serves as a crucial aspect of the broader narrative, acknowledging the need for ongoing monitoring and management to ensure a comprehensive and successful treatment trajectory for patients with this unique presentation of clear cell sarcoma.

Malignant Melanotic Schwannoma or Schwannian Melanoma?

A 43-year-old man underwent surgical removal of L4-L5 nerve root tumor which bulged to the extra and intradural spaces and extended as a dumbbell through the intervertebral foramen. Histological examination showed pleomorphic tumor cells with heavy melanin pigmentation. Most of the tumor cells were immunohistochemically positive for vimentin, S-100 protein and HMB-45 antigen; basic myelin protein was detectable in single tumor cells. Electron-microscopy revealed melanosomes in different stages of differentiation and some characteristics of Schwann cells, such as redundant basal lamina production. Taken together the tumor showed features of histological malignancy and incomplete schwannian differentiation with considerable overlap between melanoma and malignant melanotic schwannoma.

HMB-45 Staining in Angiomyolipoma, Cardiac Rhabdomyoma, Other Mesenchymal Processes, and Tuberous Sclerosis-associated Brain Lesions

HMB-45 monoclonal antibody is thought to be highly specific for melanocytic prolifer ations. In a recent study of two cases of hepatic and one case of renal angiomyolipoma, strong staining of lesional cells with this antibody was unexpectedly encountered. In follow-up evaluation, the authors studied 51 additional soft tissue, renal, and brain tumors and tumor-like processes, with emphasis on those with prominent vascular, myogenous, and fatty components or those known to be associated with tuberous sclerosis. Varying degrees of staining with HMB-45 were seen in 17 of the lesions tested. Strong staining with HMB-45 was demonstrated in four renal angiomyolipo mas. Clearly positive results were also obtained in three other processes associated with the tuberous sclerosis complex, including two cardiac rhabdomyomas and one tuberous lesion of the brain. Weak staining of several other mesenchymal and neural lesions was also observed. Electron microscopic studies showed a spectrum of granules within angiomyolipoma, some of which resembled melanosomes and others renin granules. Similar granules were observed in cardiac rhabdomyoma, cerebral tuberous lesions, and in subependymal giant cell astrocytoma. We propose that tuberous scleros is-associated tumors and tumor-like processes are interrelated, and that these and perhaps other mesenchymal proliferations may share components previously believed to be unique to melanocytic lesions. Int J Surg Pathol 1 (3):191-198, 1994

Clear Cell Sarcoma of Tendons and Aponeuroses

Fifty-eight previously unreported cases of clear cell sarcoma of tendons and apo neuroses occurring in 29 males and 29 females with a median age of 31 years are presented. The distal extremities were most frequently involved (58%), followed by the limbs and limb girdles (33%), and trunk (9%). Median tumor size was 2.5 cm (range, 0.6-9 cm). Kaplan-Meier estimates revealed a 5-year survival rate of 63%. Eleven of 43 patients (26%) had local recurrences at a median interval of 33 months. Metastases occurred in 20 of 45 cases (44%) at a median interval of 26 months; 19 of 20 patients with metastases died of the disease. The most common metastatic site was the lungs (11 cases), followed by bone (9 cases), and lymph nodes (8 cases). Clear cell sarcoma had a stereotypic morphology consisting of packeted arrangements of uniform, round to fusiform cells with eosinophilic to clear glycogen-rich cytoplasm, and prominent nucleoli, as well as multinucleated tumor cells with a wreath-like arrangement of nuclei. S100 protein was detected in all 44 cases studied, vimentin in 36, and HMB45 stained 36. Twenty-six cases were studied with antibodies directed against proliferating cell nuclear antigen. Neither the intensity of proliferating cell nuclear antigen staining, percentage of positive cells, nor the combined score of these two variables corresponded with mitotic rate or survival. Increasing size (as a continu ous variable) and necrosis were found to be independent adverse prognostic factors by multivariate analysis. Int J Surg Pathol 1 (2):89-100, 1993

Gastrointestinal melanoma or clear cell sarcoma? Molecular evaluation of 7 cases previously diagnosed as malignant melanoma

Clear cell sarcoma (CCS) is a rare tumor classically associated with the tendons and aponeuroses of distal extremities of young adults. CCS and malignant melanoma (MM) share immunohistochemical profiles and ultrastructural features, but classic CCS has characteristic morphology with low mitotic activity and minimal pleomorphism. Occasional cases show pleomorphism, high mitotic index, and/or melanin pigmentation, making CCS indistinguishable from MM based on morphology. However, CCS is genetically distinct owing to its consistent association with a t(12;22)(q13;q12) chromosomal translocation, leading to the formation of the EWS/ATF1 fusion transcript. This translocation has never been documented in cutaneous melanoma, and thus is regarded as specific for CCS. Recent evidence suggests that primary "malignant melanomas" in unusual anatomic sites, most notably the gastrointestinal (GI) tract, may be CCS. This is supported by 11 cases of primary GI CCS with the t(12;22) translocation. We used reverse-transcription polymerase chain reaction and fluorescence in situ hybridization to examine whether a proportion of cases diagnosed as MM of the GI tract in patients without a history of cutaneous MM actually represent primary GI CCS. In total, we examined 7 cases: Four with no prior history of MM, 2 with histories of cutaneous MM, and 1 with an anal MM. All 4 cases for which there was no history of cutaneous/mucosal MM harbored the EWS/ATF1 fusion transcript. We report the largest series of GI CCS and have shown that molecular studies may be warranted in cases that otherwise seem to represent MM of unusual primary locations.

Lessons to be learned: a case study approach. Malignant melanoma of soft tissue

Malignant melanoma of soft tissue, also called clear cell sarcoma (CCS) of tendons and aponeuroses, presents as a soft tissue mass, usually in the lower extremity of young females. We report two cases of CCS of the upper extremity--in a Korean and a Saudi Arabian girl. Because of the presence of melanin, melanosomes, S-100 protein and the tendency for regional nodal metastases, it has been suggested that this entity be considered a melanoma rather than a soft tissue sarcoma. The evidence for a neuroectodermal origin of these neoplasms is compelling. Despite these features, CCS has been reported as showing a distinct chromosomal translocation pattern t(12;22)(q13;q12) in certain isolated cytogenetic or molecular diagnostic case reports; however, there is no information about the breakpoints at genomic level. Such genetic studies need to be performed on primary and metastatic cutaneous, mucosal or ocular melanomas prior to considering them specific for malignant melanoma of soft tissue/CCS. Microscopically, solid nests and fascicles of pale fusiform or cuboidal cells are divided by fine fibrous tissue septa. Characteristically, the cells possess a round to oval nucleus with a central prominent nucleolus. Pleomorphism may or may not be present; the cytoplasm is clear due to the presence of glycogen but, occasionally, the cytoplasm is more eosinophilic, resembling a melanoma. A tumour size (> or = 5 cm) and the presence of necrosis are statistically significant predictors of poor prognosis. A lesion on the proximal part of an extremity progresses slower than one that is more distal (i.e. acral). An early diagnosis and initial radical surgery are essential for a favourable clinical outcome. Once regional lymph node metastases or haematogenous dissemination has occurred, the prognosis becomes dismal.

Pigmented lesions in unusual anatomic sites

This review considers pigmented melanin-containing lesions arising in extracutaneous locations. It includes reactive lesions as well as benign and malignant neoplasms. Melanocytic lesions of the mucosae, nervous system, and individual organs are discussed, and rarer pigmented tumors in unusual sites are also covered. A brief description of the histology and clinical behavior along with proposed explanations for their ectopic location are provided. Emphasis is given to the reality that detailed morphological evaluation and application of ancillary techniques can establish the melanocytic nature and biologic potential of such tumors, but cannot, by themselves, determine the primary or metastatic nature of these lesions.

Classification of clear-cell sarcoma as a subtype of melanoma by genomic profiling

PURPOSE

To develop a genome-based classification scheme for clear-cell sarcoma (CCS), also known as melanoma of soft parts (MSP), which would have implications for diagnosis and treatment. This tumor displays characteristic features of soft tissue sarcoma (STS), including deep soft tissue primary location and a characteristic translocation, t(12;22)(q13;q12), involving EWS and ATF1 genes. CCS/MSP also has typical melanoma features, including immunoreactivity for S100 and HMB45, pigmentation, MITF-M expression, and a propensity for regional lymph node metastases.

MATERIALS AND METHODS

RNA samples from 21 cell lines and 60 pathologically confirmed cases of STS, melanoma, and CCS/MSP were examined using the U95A GeneChip (Affymetrix, Santa Clara, CA). Hierarchical cluster analysis, principal component analysis, and support vector machine (SVM) analysis exploited genomic correlations within the data to classify CCS/MSP.

RESULTS

Unsupervised analyses demonstrated a clear distinction between STS and melanoma and, furthermore, showed that CCS/MSP cluster with the melanomas as a distinct group. A supervised SVM learning approach further validated this finding and provided a user-independent approach to diagnosis. Genes of interest that discriminate CCS/MSP included those encoding melanocyte differentiation antigens, MITF, SOX10, ERBB3, and FGFR1.

CONCLUSION

Gene expression profiles support the classification of CCS/MSP as a distinct genomic subtype of melanoma. Analysis of these gene profiles using the SVM may be an important diagnostic tool. Genomic analysis identified potential targets for the development of therapeutic strategies in the treatment of this disease.

Molecular diagnosis of clear cell sarcoma: detection of EWS-ATF1 and MITF-M transcripts and histopathological and ultrastructural analysis of 12 cases

Clear cell sarcoma (CCS), also known as melanoma of soft parts, is an uncommon deep soft tissue tumor presenting typically in the lower extremities of young adults. Previous cytogenetic studies have established the specificity of the recurrent t(12;22)(q13;q12), resulting in a EWS-ATF1 fusion, for CCS. The prevalence of the EWS-ATF1 fusion in CCS remains unclear, since most genetically confirmed CCS have been reported as isolated cytogenetic or molecular diagnostic case reports. We therefore studied histologically confirmed CCS from 12 patients for the presence of EWS-ATF1 by reverse-transcriptase polymerase chain reaction (RT-PCR), using RNA extracted from either frozen (four cases) or formalin-fixed paraffin-embedded (eight cases) material. All primary tumors were located in the deep soft tissues of the extremities. Histologically, 10 cases had a typical epithelioid nested appearance. Most or all cases showed immunostaining for HMB45 (12 of 12), S-100 protein (10 of 12), and MITF (12 of 12). Ultrastructural analysis showed melanosomes in six of seven cases. The presence of an EWS-ATF1 fusion transcript was identified by RT-PCR in 11 of 12 cases (91%), all of which showed the same fusion transcript structure, namely the previously described in-frame fusion of EWS exon 8 to ATF1 codon 65. RT-PCR analysis for the melanocyte-specific splice form of the MITF transcript was positive in all cases tested (4 of 4). These data confirm that EWS-ATF1 detection can be used as a highly sensitive diagnostic test for CCS and that CCS expresses the melanocyte-specific form of the MITF transcript, further supporting its genuine melanocytic differentiation.

Clear cell sarcoma shows immunoreactivity for microphthalmia transcription factor: further evidence for melanocytic differentiation

Microphthalmia transcription factor, a melanocytic nuclear protein critical for the embryonic development and postnatal viability of melanocytes, is a master regulator in modulating extracellular signals. Recently, microphthalmia transcription factor expression was shown to be both a sensitive and specific marker of epithelioid melanoma. We investigated the sensitivity of D5, an anti-microphthalmia transcription factor antibody, for diagnosis of clear cell sarcoma (also known as malignant melanoma of soft parts). Immunoreactivity in a nuclear pattern for D5 was present in 8 of 12 (75%) tumors. D5 staining was strong in three tumors, moderate in two, and weak in three. S-100 protein expression was seen in all 12 cases that had clear cell sarcoma examined. HMB-45 staining was seen in 11 of 12 (92%) tumors. Focal Melan-A positivity was seen in 3 of 7 (43%) tumors. Although D5 was shown in a previous study to be a highly sensitive and specific marker for epithelioid melanomas, the results of this study expand the spectrum of tumors showing immunoreactivity for D5. D5 immunoreactivity in clear cell sarcoma provides further evidence for melanocytic differentiation in this unusual tumor.

Electron microscopy in tumor diagnosis: indications for its use in the immunohistochemical era

The electron microscope reveals much more information on tumor cell structure than can be obtained with the light microscope, and some of the data are useful in diagnostic studies. In this review, major contributions of electron microscopy in the main tumor categories are discussed. To select between immunocytochemistry and electron microscopy, the probable contributions of each in the context of the particular case must be assessed. Usually, electron microscopy will only be requested after a battery of immunostaining procedures has been performed and found to be insufficient, but there are occasions when ulstrastructural study is logically the first choice after routine light microscopy. It is worth taking tissue for possible electron microscopy from any tumor that is known or anticipated to be a diagnostic problem.

Role of electron microscopy in the evaluation of soft tissue neoplasms, with emphasis on spindle cell and pleomorphic tumors

The current significant role of transmission electron microscopy in the evaluation of soft tissue tumors when correlated with conventional histological and immunohistochemical studies is discussed for the following entities: myxofibrosarcoma, storiform-pleomorphic fibrosarcoma (malignant fibrous histiocytoma), and myofibrosarcoma; dermatofibrosarcoma protuberans; hemangiopericytoma; monophasic synovial sarcoma; extrarenal rhabdoid tumor; soft tissue perineurioma; and gastrointestinal stromal tumors, notably the so-called autonomic nerve variant.

Clear cell sarcoma of the ileum: the crucial role of cytogenetics for the diagnosis

We report a case of clear cell sarcoma that arose in the ileum and metastasized to the liver. The tumor cells did not contain melanin or glycogen; expressed S-100 protein, but not HMB45; and contained possible atypical melanosomes when examined by electron microscopy. They carried a clonal chromosomal rearrangement: 50,XY,t(2;7)(q37;q22),+8,+8,+9,+11, t(12;22)(q13;q12). The diagnosis was greatly facilitated by the cytogenetic analysis. The translocation t(12;22)(q13;q12-13) has been reported as specific for clear cell sarcomas.

Newly established MST-1 tumour cell line and tumour-infiltrating lymphocyte culture from a patient with soft tissue melanoma (clear cell sarcoma) and their potential applications to patient immunotherapy

The establishment and characterisation of paired autologous tumour cell line (MST-1) and tumour-infiltrating lymphocyte (TIL) culture from a tumour mass of a 14-year-old Taiwanese girl with soft tissue melanoma are described. MST-1 cells grown in vitro were heterogeneous in morphology, ranging from floating round cells, loosely attached round/oval or elongated cells with prominent pseudopod-like processes, to well-attached spindle and elongated dendritic cells without obvious pseudopods. Immunostaining revealed that major melanoma-associated antigens, such as S100 protein, HMB-45, melanotransferrin, chondroitin sulphate proteoglycan, and the gangliosides GD2 and GD3, were consistently expressed by the tumour tissue, severe combined immunodeficiency (SCID) mouse xenograft and derived cell lines. Flow cytometric analysis of the tumour DNA content showed an index of 1.8 relative to normal peripheral blood lymphocyte DNA. Chromosome analysis revealed all cells at a hypotetraploid level with several clonal chromosome aberrations, including deletions at 10p and 12q, an addition at 12q, translocations t(1;14) and t(5;6). Electron microscopy showed melanosome structures. This observation and the expression of the major melanoma-associated antigens were all indicative of the melanocytic origin of MST-1 tumour. Interleukin-2 (IL-2) expanded TILs had the predominant CD8+ phenotype and the capacity to lyse cells of the cultured autologous tumour. The availability of the soft tissue melanoma cell line, the SCID mouse xenograft tumour system as well as autologous TILs described herein would provide useful materials for identifying T-cell-defined antigens as well as a model system for devising individualised cancer biotherapeutic strategies. This cell line can also be used for further studies aimed at uncovering the histogenesis of this rare cancer.

Malignant melanoma of soft parts involving the head and neck region: review of literature and case report

Malignant melanoma of soft parts (MMSP) was originally described as a distinct entity by Enzinger in 1965 and was termed "clear cell sarcoma of tendons and aponeuroses" because of its association with tenosynovial structures. It has been shown immunophenotypically and ultrastructurally that this tumor is derived from neuroectoderm and shares a number of features with cutaneous melanoma. Over 95% of MMSPs present in the extremities, with the head and neck region (1.9%) being an unusual site. This study presents an additional case of MMSP of the head and neck region involving the posterior cervical region in a 15-year-old Hispanic male and reviews the literature on MMSP. Ultrastructural examination showed rudimentary cell attachments, smooth cell membranes, discontinuous basal lamina, scanty glycogen, and occasional premelanosomes in some tumor cells. Cytogenetic analysis showed a reciprocal translocation between the long arms of chromosomes 12 and 22 [t(12:22)(q13;q12.2)], characteristic for MMSP and not seen in cutaneous melanoma. Survival in MMSP has been correlated with tumor size, tumor necrosis, and ploidy status. Overall reported clinical outcome for this tumor is as follows: died of disease, 45%; alive with disease, 23%; no evidence of disease, 30%; and died of other causes, 2%. MMSP represents a distinct entity with a characteristic ultrastructural appearance and a tumor defining cytogenetic translocation.

Ossifying fibromyxoid tumor of soft parts with stromal cyst formation and ribosome-lamella complexes

Ossifying fibromyxoid tumor of soft parts (OFMT) is a recently named soft tissue tumor of uncertain nature. A case is described that presented in a 13-year-old boy as a discrete mass in the muscles of the lower abdominal wall. Light microscopy showed, in addition to the typical features of this entity, microcysts formed by accumulations of the myxoid stroma. Bone formation was lacking. Tumor cells were strongly immunoreactive for vimentin and glial fibrillary acidic protein and weakly so for S-100 protein. A few cells stained for desmin and alpha-smooth muscle actin. Ultrastructurally, there were abundant, patternless cytoplasmic intermediate filaments; short, poorly interdigitating processes; and discontinuous segments of thick external lamina. In addition, several cells contained typical ribosome-lamella complexes in small groups. Ribosome-lamella complexes occur in neoplastic hematopoietic cells but are uncommon in solid tumors, particularly those affecting the soft tissues. These findings extend the range of appearances described for OFMT, which is added to the list of tumors in which ribosome-lamella complexes have been demonstrated. The balance of evidence suggests that OFMT may represent a peripheral nerve sheath tumor of low-grade malignancy, although the picture is incomplete.

Angiomyolipoma of the kidney. Immunoreactivity with HMB-45. Light- and electron-microscopic findings

Immunoreactivity with HMB-45 has recently been described in renal angiomyolipoma, a tumour of smooth muscle cells. HMB-45 is a monoclonal antibody that reacts specifically with melanosomes. In order to determine whether the tumour cells contain melanosomes and synthesize melanin, seven tumours were studied by light microscopy and immunohistochemically with the antibodies HMB-45, KP1 (CD68), PG-M1 (CD68), Ki-M1P, anti-lysozyme, anti-smooth-muscle actin, anti-vimentin, anti-S100 protein and KL1 (anti-keratin). Two tumours were also studied by electronmicroscopy and one by immuno-electronmicroscopy. Histochemical investigation for dopa oxidase was performed on cryostat sections. The tumours contained varying numbers of HMB-45-positive muscle cells. Reactivity was noted in lysosomal granules and rough endoplasmic reticulum. Typical premelanosomes were found in the tumour cells by electronmicroscopy. Groups of tumour cells stained for dopa oxidase. The tumour cells were not reactive for lysozyme, but reacted with KP1, PG-M1 and Ki-M1P. Immuno-electronmicroscopy showed that reactivity for KP1 was located within lysosomal granules. The findings show that the tumour cells of renal angiomyolipoma contain premelanosomes and that they are able to synthesize melanin, because they contain dopa oxidase. Immunoreactivity with KP1, PG-M1 and Ki-M1P can be attributed, in the absence of staining for lysozyme, to the large number of lysosomal granules. The tumour cells were not found to be related to macrophages or myeloid cells.

Establishment and characterization of a clear-cell sarcoma (malignant melanoma of soft parts) cell line

A clear cell sarcoma (CCS) cell line, designated as NCS-1, was established in monolayer culture from a xenograft line originating from a metastatic CCS. Marked karyotypic aberrations and tumorigenicity in nude mice revealed the malignant derivation of the NCS-1 cell line. These cells contained abundant glycogen and were amelanotic by light microscopy. By electron microscopy, however, melanosomes in various developmental stages were seen, and some of them were partially melanized. The electron microscopic dopa reaction revealed the presence of tyrosinase activity. Enzyme-linked immunoadsorbent assay revealed that NCS-1 cells expressed a 75-kDa glycoprotein which was identified as a marker of highly differentiated melanoma cells. From these results, NCS-1 cells were found to retain both cytochemical and morphological properties of CCS. Application of NCS-1 cells to a panel of monoclonal antibodies recognizing melanocytic differentiation antigens showed that they corresponded approximately to highly differentiated melanoma cells. In conclusion, the present study strongly supports the close relationship between CCS and malignant melanoma.

Establishment and characterization of a new human clear-cell sarcoma cell-line, HS-MM

We have established and morphologically characterized a new human clear-cell sarcoma cell-line, HS-MM, from the pleural effusion of a 39-year-old man with pulmonary metastasis derived from the primary popliteal tumour. The HS-MM cells were round or spindle-shaped, with round nuclei containing extremely prominent nucleoli. Light microscopically, the heterotransplanted nude mouse tumours showed essentially the same features as those of the original sarcoma, revealing an alveolar pattern of tumour cells with abundant clear cytoplasm. Both in vitro and in vivo, the cells reacted with anti-S-100 protein and melanoma-specific HMB 45 antibodies by immunohistochemistry. Ultrastructurally, the cells contained round euchromatin-rich nuclei with large nucleoli revealing conspicuous nucleolonema, and a large amount of glycogen and a few lysosomal dense bodies, but no premelanosomes in their cytoplasm. The HS-MM cell line was thus fully proven to exhibit the unique characteristics of a clear sarcoma both in vitro and in vivo, being also compatible with an amelanotic melanoma. This cell line will therefore be extremely useful for clinicopathological and histogenetic studies on clear cell sarcomas.

Hepatic angiomyolipoma with striated granules and positivity with melanoma--specific antibody (HMB-45): a report of two cases

Angiomyolipoma occurs rarely in the liver, with only 25 previous cases being reported in the English literature. The article describes two additional cases, one of which was multicentric, with results of ultrastructural and immunocytochemical studies. Many of the tumor cells contained numerous electron-dense granules, some with transverse striations like those found in melanosomes. Both tumors stained positively for S-100 protein and melanoma-specific antibody HMB-45. One case also expressed vimentin and neuron-specific enolase. Both were negative for cytokeratin, carcinoembryonic antigen, alpha-fetoprotein, desmin, muscle-specific actin, factor VIII antigen, and chromogranin. Comparison of our ultrastructural findings with those of classic renal angiomyolipoma raises the possibility that the melanosomelike structures may represent renin granules rather than melanosomes, although the latter are not excluded. Expression of HMB-45 in angiomyolipoma has important biologic and diagnostic implications, whether or not it reflects melanocytic differentiation.

Clear cell sarcomas and metastatic soft tissue melanomas. A flow cytometric comparison and prognostic implications

Eleven soft tissue clear cell sarcomas (CCS) were examined flow cytometrically for their DNA content with a correlation of the DNA with the patients' survival. Diploidy was expressed in six sarcomas and it conferred a longer survival (mean, 68.6 months) than aneuploid sarcomas (mean, 8.2 months). For comparison, 13 metastases to soft tissues from cutaneous melanomas were assessed by flow cytometric study. The aneuploid neoplasms of both entities were categorized into low and high degree based on extent of the DNA index (DI). Low degree was defined by a DI of less than or equal to 1.5 and high degree by a DI of greater than 1.5. Significant differences in DNA content between CCS and metastatic melanomas were observed. Melanomas were preponderantly aneuploid (11/13) of high degree (mean DI, 1.7) whereas CCS manifested more diploidy (six of 11) and their aneuploidy was of a low degree (mean DI, 1.2; P = 0.001). Clear cell sarcomas and melanomas were also examined for their immunoreactivity to S-100 protein and HMB-45 antigen. All CCS reacted with S-100 protein and HMB-45. In CCS the reactions were diffuse for both in six tumors, diffuse with HMB-45 and moderate to S-100 protein in three tumors and diffuse with S-100 and moderate with HMB-45 in two tumors. All melanomas reacted diffusely to S-100 protein except for one heavily pigmented tumor which reacted only focally. The reaction to HMB-45 was diffuse in nine and focal in three melanomas. These data suggest that measurements of DNA content in CCS may be valuable in predicting clinical outcome and that there are quantitative differences in DNA content between CCS and metastatic melanoma in soft tissues.

Breast sarcoma. A clinicopathologic review of 25 cases

Sarcoma of the breast represents less than 1% of primary mammary malignancies; this study reports 25 such cases. The largest group had malignant fibrous histiocytoma (44%), followed by liposarcoma (24%) and fibrosarcoma (16%). Also represented were clear cell sarcoma, neurogenic sarcoma, leiomyosarcoma, and alveolar soft part sarcoma (4% each). Of 19 patients treated by wide local excision or simple mastectomy with or without adjuvant radiotherapy, 11 had local recurrence develop, of which one patient died and nine of the remaining ten had metastases develop. Of the remaining eight patients in this group with no local recurrence, only two had metastases develop. Of the six patients treated by radical or Patey mastectomy, none had local recurrence develop, but two died of metastases. No patient had metastases develop more than 5 years after diagnosis. Regional lymph node involvement with tumor was observed in only one patient (with malignant fibrous histiocytoma) despite regional lymphadenopathy in seven. The overall mortality at 5 years is 64% but does not increase thereafter. The authors' findings suggest that failure to establish local control is associated with a poor prognosis and that wide local excision or simple mastectomy does not provide sufficient clearance to be used as first-line treatment. Excision of the axillary lymphatics and adjuvant radiotherapy are unlikely to be beneficial.

Pigmented melanocytic schwannoma of the uterine cervix

A 47-year-old woman had a lesion of the uterine cervix that presented clinically as a protruding or aborted leiomyoma. Grossly the tumor occupied a substantial portion of the cervical and endocervical region. Histologically it showed a spindle cell neoplasm arranged in large fascicles that penetrated deeply into the fibromuscular wall of the cervix. The tumor cells had abundant pink cytoplasm that contained considerable brown melanin granules confirmed by Fontana's stain. Cytologically nuclear pleomorphism, hyperchromatism, and giant nuclear forms were observed. Mitoses were also seen. Localized nuclear palisading was present. Electron microscopic examination of paraffin-embedded material revealed numerous premelanosomes and opaque granules that were compatible with mature melanosomes, thus confirming melanogenesis in the tumor. Tumor cells exhibited focal projections, and the connective tissue showed abnormal spacing of collagen. Basal lamina material was noted focally on tumor cell surfaces. Immunocytochemistry showed a positive reaction to S-100 protein and HMB-45 in tumor cell cytoplasm.

Synovial sarcoma: an immunohistochemical and ultrastructural study

Thirty-nine primary synovial sarcomas (15 biphasic, 24 monophasic), and 19 metastatic synovial sarcomas were studied with a battery of antibodies directed to keratin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), vimentin, desmin, muscle-specific actin, smooth muscle actin, S-100 protein, Leu-7, chromogranin A, laminin, collagen IV, Ulex europaeus agglutinin I (UEAI), and the HMB-45 antimelanoma antibody. Twenty-two primary and 18 metastatic synovial sarcomas were also examined by electron microscopy. Epithelial and/or spindle cells in every biphasic tumor, primary and metastatic, reacted for keratin and EMA, but only six primary tumors (five biphasic and one monophasic) showed weak reactivity for CEA which, in the biphasic tumors, was confined to the epithelial component. Of the monophasic tumors, 15 primary (63%) and four metastatic (25%) stained for keratin, whereas seven primary (29%) and two metastatic (13%) tumors reacted for EMA. Only one primary monophasic synovial sarcoma stained for CEA. Tumors that stained for EMA or CEA also stained for keratin which is, therefore, the most useful epithelial marker. Immunostaining for epithelial markers, UEAI, collagen IV, and laminin serves to delineate the epithelial component when it is obscure in routine sections. Electron microscopy facilitates the diagnosis when epithelial markers are not expressed and aids in separating monophasic synovial sarcomas from other sarcomas that they resemble by light microscopy.

Electron microscopy of large cell undifferentiated and giant cell tumors

Electron microscopy is a valuable morphologic method for the diagnostic evaluation of undifferentiated tumors composed of polygonal or oval large cells and mononuclear or multinucleated giant cells. Although few ultrastructural details are pathognomonic, electron microscopic findings may add significantly to the formulation of the final diagnosis if used in the context of other pathomorphologic and clinical data. Contributions of electron microscopy to tumor diagnosis are summarized and illustrated with appropriate examples from personal experience in a routine university hospital laboratory.

Neural crest origin of clear cell sarcoma of tendons and aponeuroses. Ultrastructural and enzyme cytochemical study of human and nude mouse-transplanted tumours

In order to clarify the histogenesis of clear cell sarcoma of tendons and aponeuroses (CCS), two cases of human and one nude mouse-transplanted CCS line were studied using an ultrastructural and enzyme cytochemical approach. Most of the tumour cells obtained from the primary and transplanted CCS demonstrated melanosomes in various stages of development within the cytoplasm, whereas no melanosomes could be identified in the metastatic CCS. However, cholinesterase and tyrosinase activities could be demonstrated not only in the melanotic primary and transplanted CCS but also in the amelanotic metastatic CCS. The results therefore support the hypothesis that CCS is a soft tissue tumour derived from the neural crest.

Melanotic schwannoma coexpression of vimentin and glial fibrillary acidic protein

A 35-year-old man was operated for a thoracic wall tumor which bulged into the pleural cavity. Histologic examination showed a spindle cell tumor with numerous psammoma bodies and a heavy melanin pigmentation. Electron microscopy revealed melanosomes and a continuous basal lamina surrounding all tumor cells, compatible with the diagnosis of a melanotic schwannoma. The tumor cells were S-100 protein-positive, and there was an abundant pericellular laminin-positivity. Practically all tumor cells were vimentin-positive, while cytokeratin, desmin and neurofilaments were absent. Glial fibrillary acidic protein was found in single tumor cells, suggesting the presence of focal glial differentiation in melanotic schwannoma.