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Clear Cell Sarcoma of Tendons and Aponeuroses with t(12;22) (q13;q12) Diagnosed Initially as Malignant Melanoma

Boguslaw Nedoszytko, Krzysztof Mr6zek, Andrzej Roszkiewicz, Andrzej Kopacz, Maciej Swierblewski, and Janusz Limon

ABSTRACT: Cytogenetic analysis performed on a specimen from an inguinal lymph node metastasis of a tumor diagnosed initially as a cutaneous malignant melanoma revealed the following karyotype: 50,XX, +2, ÷7, +8. +8,t(12;22) (q13;q12). The finding of t(12;22) (q13;q12), an abnormality specific of clear cell sarcoma of tendons and aponeuroses (CCS), prompted reanalysis of histologic slides, and a final diag- nosis of CCS was made. Our case illustrates the usefulness of cytogenetic analysis in the differential diagnosis of CCS and malignant melanoma. In addition, extra copies of chromosomes 8, 7, and 2, present in our case as well as in previously reported tumors, seem to play an important, although at present not understood, role in the development of CCS. @ Elsevier Science Inc., 1996

INTRODUCTION

Clear cell sarcoma of tendons and aponeuroses (CCS), a rare soft tissue neoplasm arising in the extremities of young adults, also has been termed malignant melanoma of soft parts because it shares certain light-microscopic, immunohistochemical, and ultrastructural features with cutaneous malignant melanoma. Despite these similarities and a possible common origin from a neural crest, the two entities seem to differ cytogenetically. The majority of thus far analyzed CCSs have displayed a specific translocation, t(12;22)(q13;q12), that re,mlts in a fusion between a tran- scription factor gene ATF1, located at 12q13, and a gene with an RNA-binding domain called EWS and mapped to band 22q12 [1-4]. In contrast, the t(12;22) has not been seen in any of more than 160 karyotypically aberrant cases of cutaneous malignant melanoma [5].

We present herein another case of CCS with t(12;22), initially diagnosed as cutaneous malignant melanoma, that illustrates the usefulness of cytogenetic analysis in the differential diagnosis of these tumor types.

From the Department of Biology and Genetics (B. N., K. M., J. L), Pathology (A. R.), and Oncological Surgery (A. K., M. S.), Medical University, Gda~sk, Poland.

Address reprint requests to: Dr. Janusz Limon, Department of Biology and Genetics, Medical University, 1 DQbinki St., 80-211 Gdmisk, Poland. Dr. Mr6zek's present address: Cytogenetics Research Laboratory, Division of Medicine, Roswell Park Cancer Institute, Buffalo, IVY 14263.

Received March 9, 1996; accepted April 5, 1996.

Cancer Genet Cytogenet 91:37-3!) (1996) @ Elsevier Science Inc., 1996 655 Avenue of the Americas , New York, NY 10010

CASE REPORT AND CYTOGENETIC ANALYSIS

The patient, a 24-year-old woman, was admitted to the Department of Oncological Surgery in November 1994. Six months prior to admission, a nonradical excision of an ulcerated skin lesion localized over the medial ankle of her right foot was performed in a provincial hospital. The excised tissue was not examined histopathologically. Because the ulcerated lesion persisted and enlarged, an incisional biopsy was performed in October 1994. The light microscopic examination was read as consistent with malignant melanoma. Upon admission, the patient pre- sented with a 8 x 8-cm ulcerated, firm swelling over the dorsomedial aspect of her right foot. Radiographs showed partial destruction of the talus. Physical examination and lymphography revealed metastases to the right inguinal lymph nodes. In December 1994, the patient underwent a below the knee amputation and right ilioinguinal lym- phadenectomy. A total of 23 lymph nodes were excised; metastases were found in 3 inguinal lymph nodes. A spec- imen from a metastatic lymph node was obtained for cyto- genetic analysis. The patient remains clinically free of disease 14 months after surgery.

Macroscopic examination of the primary tumor re- vealed a grey-white multinodular mass, measuring 8 x 8 3.2-cm, with widely separated, small foci of necrosis and hemorrhage. The tumor was intimately associated with lo- cal tendons. Histopathologically, the tumor was composed of both nests of rounded cells with a pale cytoplasm and round or oval vesicular nuclei with prominent nucleoli, and fascicles of spindle-shaped cells with faintly eosino- philic cytoplasm and darker nuclei with less prominent

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38 B. Nedoszytko et al.

nucleoli. The individual nests and fascicles of tumor cells were separated by thin fibrous septa. Mitotic figures were relatively sparse. In a proportion of the tumor cells, the presence of melanin was demonstrated by Fontana stain- ing. Immunohistochemical studies revealed reactivity to S-100 protein and neuron specific enolase. All these stud- ies, together with the results of cytogenetic analysis (see below), supported the final diagnosis of CCS.

The tumor specimen was processed for cytogenetic analysis as described by Limon et al. [6]. In brief, the tissue was dissected with scissors, disaggregated in collagenase overnight, and cultured in Eagle's medium supplemented with 10% fetal bovine serum, L-glutamine, and antibiot- ics. The chromosomes were obtained after 6 days of tissue culture, and G-banded with trypsin and Wright's stain. Seven metaphase cells were analyzed, and all of them displayed the karyotype 50,XX,+2,+7,+8,+8,t(12;22) (q13; q12) (Fig 1].

DISCUSSION

Although the t(12;22) (q13;q12) has been accepted as a specific primary aberration in CCS, the number of CCS cases reported in the cytogenetic literature is still very low

[1]. Our case represents the sixteenth successfully karyo- typed patient with CCS and the tenth that displays the t(12;22)(q13;q12) in the karyotype, thus bringing the per- centage of t(12;22)-positive cases to 62.5%, and confirm- ing a close relationship between this cytogenetic rearrangement and CCS. Interestingly, the tumor in our patient had been initially diagnosed as cutaneous malig- nant melanoma, and it was not until cytogenetic analysis revealed the presence of the t(12;22) that the correct diag- nosis of CCS could be made. Hence the case presented herein supports the notion that the t(12;22) is a reliable karyotypic marker in the differential diagnosis of CCS from cutaneous malignant melanoma.

All numerical abnormalities present in addition to the t(12;22) our case have already been reported in CCS. An extra copy or two copies of chromosome 8 have been the most prevalent, being present in 13 patients (81%) [1-3, our case]. Notably, tetrasomy 8 or 8q has been more com- mon than trisomy 8 (7 versus 6 cases). Because in two previously reported patients an additional material of chromosome 8 was derived from its long arm as a result of unbalanced structural aberrations, namely der(8;17)(q10; ql0) and i(8)(q10) [3, 7], it is likely that the genes whose duplication presumably contribute to CCS oncogenesis are

Figure I G-banded karyotype demonstrating clonal aberrations detected in our case of clear cell sarcoma of ten- dons and aponeuroses: 50,XX,+2,+7,+8,+8,t(12;22)(q13;q12). Arrowheads indicate the t(12;22).

1 2 3 4 5

5 7 8 9 10 11

13 14 15 16 17

t'9 28 21

Clear Cell Sarcoma wi th t(12;22) 39

located in 8q. Likewise, in the case of t r isomy 7, another nonrandom secondary abnormal i ty in CCS that has been observed in altogether 9 pat ients (56%), a gain of the long arm mater ial seems to be of impor tance due to the fact that in two pat ients not the whole chromosome 7 but only a segment, 7p11-7qter , was dupl ica ted [7, 8]. Together wi th the present case, t r isomy 2 has been found in five tumors (31%) indicat ing that this t r isomy represents the th i rd most frequent secondary abnormal i ty in CCS.

The pat tern of secondary chromosome changes in CCS resembles to some extent that of three other mal ignant musculoskele ta l tumors, i.e., Ewing's sarcoma, synovial sarcoma, and myxoid l iposarcoma. Similar i t ies inc lude re- current gains of chromosomes 7 and 8, which have been observed in all four tumor types, and a gain of chromo- some 2, which has been repeatedly descr ibed in CCS, Ew- ing's sarcoma, and synovial sarcoma [9, 10]. However, there are also differences. Tr isomy 2 has never been found in myxoid l iposarcoma, and the frequencies of t r isomy 7, t r isomy 8, and especial ly tetrasomy 8 appear to be consid- erably higher in CCS than in Ewing's sarcoma and syn- ovial sarcoma [9, 10]. Moreover, the der(16)t(1;16), a nonrandom structural abnormal i ty in Ewing's sarcoma and myxoid l iposarcoma but not in synovial sarcoma [11], has thus far never been seen in CCS [1-3, 7, 8, 12]. The overall cytogenetic picture of CCS is also different from the aforement ioned tumc,r types in that only one pat ient wi th CCS (6%) had the t(12;22) as a sole abnormal i ty [12], whereas as many as 48% of myxoid l iposarcomas [10], 32% of synovial sarcomas [9], and 14% of Ewing's sarco- mas [5] d id not have any cytogenet ical ly detectable changes in addi t ion to their respect ive pr imary abnormali- ties. Thus secondary aberrat ions seem to p lay a greater, al- though at present not unders tood, role in CCS than in the other sarcomas.

This study was supported by Grant KBN 4PO5A 07910 from the Polish State Committee for Scientific Research.

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