Case 106 - Discussion

Uploaded: 2007-09-29, Updated: 2007-09-29



CD99 S100
SMA Vimentin

Microscopic Description (WJH)
Examination of the specimen shows a 1.9 cm, well-encapsulated intramuscular mass. The tumor consists of nodules of spindle-shaped tumor cells with an overall intersecting, fascicular pattern. The tumor shows enlarged nuclei with prominent macronucleoli. The mitotic count is low, approximately 1-2 per HPF. There are no areas of necrosis, hemorrhage or lymphovascular invasion. The tumor cells demonstrate a positive immunohistochemical staining for pancytokeratin (focal), S100, vimentin, and CD99. The tumor cells are negative for melanosome, desmin, SMA, CD34, and EMA.

The tumor is composed of spindle-shaped cells with long, thin intertwining processes. There is extensive basal lamina covering cell bodies. The nuclear to cytoplasmic ratio is high, with pleomorphic roughly oval- to spindle-shaped nuclei with indentations. Most nuclei are euchromatinic with single, large nucleoli. The cytoplasm contains a moderate amount of mitochondria and rough endoplasmic reticulum. Definite long-spacing collagen is not seen. Rare secondary lysosomes are present. (WJH and SR)

Normal male chromosome complement: 46,XY[17]
Cytogenetic analysis did not reveal any evidence of a consistent detectable numerical or structural chromosomal anomaly at this band level.

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