Pathology of Clear Cell Myomelanocytic Tumour:
epithelioid cell tumor (PEComa)
myomelanocytic tumour (CCMMT)
belongs to the perivascular epithelioid cell family of tumours (PEComa).
The tumours are usually located in or adjacent to the falciform
These tumours are common in children and young
adults. One case has been reported in the urinary bladder.
Other PEComas includes
(renal and extrarenal) ,
lymphangioleiomyoma, and clear cell 'sugar' tumours of pancreas, uterus
PEComas are often associated with patients having tuberous sclerosis.
Both benign and malignant tumours have been described.
are diagnosed by histologically confirmed lymph node metastases and
radiological evidence of pulmonary metastases.
Histopathological features: These tumours are closely located to vascular
structures and are characterized by spindle to epithelioid cells with
clear to pale eosinophilic cytoplasm arranged in fascicular or nested
Immunohistochemically, the tumour cells expressed HMB45 and
smooth muscle actin and micropthalmia transcription factor.
In some cases Melan A is positive.
S100 protein and desmin are negative.