Soft Tissues: Melanoma: Malignant melanoma of soft parts

1999-11-01   Jérôme Couturier 

Summary

Note

Malignant melanoma of the soft parts is an old name for Clear cell sarcoma of the soft tissue

Classification

Classification

this tumour, initially described by Enzinger as clear cell sarcoma of tendons and aponeuroses, is of uncertain origin, but its immunohistochemical profile shows its melanocytic nature; however it has no genetic relationship with the cutaneous malignant melanoma

Clinics and Pathology

Embryonic origin

being of melanocytic origin, this tumour should be classified as a neuroectodermal tumour

Etiology

unknown

Epidemiology

it is a very rare tumour representing a minority of all soft tissue sarcomas

Clinics

the malignant melanoma of soft parts (MMSP) preferentially occurs in young adults, between ages of 20 and 40 years; the tumour develops mainly in the extremities, especially the legs (foot, knee, heel, ankle); it is usually deeply seated, and often bound to tendons and aponeuroses

Pathology

the tumours show compact nests and strands of round or fusiform cells with a clear cytoplasm, separated by fibrocollagenous tissue often connected to adjacent tendons or aponeuroses; mitotic index is generally low; the cells of nearly all cases express S-100 protein and the melanoma-associated antigen HMB45

Treatment

the treatment protocols vary greatly according to the intitutions; however, the melanoma of soft parts is a highly malignant tumour which requires surgical excision combined with radiotherapy and/or chemotherapy

Evolution

many patients develop recurrences and regional and distant metastases, in lymph nodes, lung, and bones; in the series of Enzinger, the average time between diagnosis and recurrence was 2.6 years, between diagnosis and metastasis, 3.5 years

Prognosis

the prognosis is poor; in the series of 115 patients studied by Enzinger, 46% had died; of the 62 living patients, 21 experienced one or more recurrences, and 7 had a metastatic disease

Cytogenetics

Cytogenetics morphological

this tumour is characterised by the presence of a chromosome translocation t(12;22)(q13;q12), which involves genes ATF-1, on chromosome 12, and EWS, on chromosome 22

Genes Involved and Proteins

Gene name

EWSR1 (Ewing sarcoma breakpoint region 1)

Location

22q12.2

Protein description

RNA binding protein

Gene name

ATF1 (activating transcription factor 1)

Location

12q13.12

Protein description

transcription factor

Result of the chromosomal anomaly

Description

the chimaeric protein is composed of the N-terminal domain of EWS linked to the bZIP domain of ATF-1

Oncogenesis

binds to ATF sites present in cAMP-responsive promoters via the ATF1 bZIP domain and activates transcription constitutively, dependent on the activation domain (EAD) present in EWSR1

Bibliography

Pubmed IDLast YearTitleAuthors
104915221999Clear cell sarcoma (malignant melanoma) of soft parts: A clinicopathologic study of 30 cases.Deenik W et al
85523871996The EWS-ATF-1 gene involved in malignant melanoma of soft parts with t(12;22) chromosome translocation, encodes a constitutive transcriptional activator.Fujimura Y et al
84015791993EWS and ATF-1 gene fusion induced by t(12;22) translocation in malignant melanoma of soft parts.Zucman J et al

Citation

Jérôme Couturier

Soft Tissues: Melanoma: Malignant melanoma of soft parts

Atlas Genet Cytogenet Oncol Haematol. 1999-11-01

Online version: http://atlasgeneticsoncology.org/solid-tumor/5024/soft-tissues-melanoma-malignant-melanoma-of-soft-parts