Piloleiomyomas are
benign smooth muscle tumors arising from the arrectores pilorum muscles
in the skin.
The tumour usually presents as multiple reddish brown nodule. These are
usually painful or sensitive to touch and cold.
Solitary lesions are rare and are usually larger than the multiple form
(upto 2cm or more in diameter).
These are usually noted in the second and third decade of life.
Common sites include face, back, and the extremities.
Microscopic features:
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These are
circumscribed non encapsulated tumours characterized by bundles and and
fascicles of smooth muscle cells.
Tumour cells are characterized by eosinophilic cytoplasm with vesicular
nuclei.
Rarely, occasional mitotic figures may be present.
Immunohistochemistry reveals that the tumour cells are positive for
actin and desmin.
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