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Immunofluorescence and electron microscopic findings in a congenital arrector pili hamartoma
S J Fishman1, R G Phelps, M Lebwohl
1Department of Dermatology, Mount Sinai Medical Center, New York, NY 10029.
Insights
Congenital arrector pili hamartoma likely originates from the arrector pili muscle. This finding aids in the histopathological diagnosis of this rare skin neoplasm.
Area of Science:
- Dermatopathology
- Histogenesis
- Neoplasms
Background:
- Congenital arrector pili hamartoma presents as dermal nodules in a dermatomal pattern.
- Understanding the histogenesis of this hamartoma is crucial for accurate diagnosis.
Observation:
- A lesion from a 3-year-old boy was analyzed using light microscopy, immunofluorescence, and electron microscopy.
- Immunofluorescence utilized antibodies against basal lamina, interstitial matrix components, and smooth-muscle myosin.
- Electron microscopy examined cellular morphology and ultrastructure.
Findings:
- Antibodies against basal lamina and fibronectin showed perimysial fluorescence around leiomyocytes.
- Anti-smooth-muscle myosin revealed intense cytoplasmic fluorescence.
- Electron microscopy identified fusiform cells with myofilaments, dense bodies, and basal lamina, characteristic of smooth muscle.
Implications:
- These findings suggest the hamartoma originates from the arrector pili muscle.
- This research can serve as an adjunct in the histopathological diagnosis of congenital arrector pili hamartoma.
Abstract:
A congenital arrector pili hamartoma is a neoplasm that presents as multiple or solitary dermal nodules in a dermatomal distribution. To elucidate and clarify its histogenesis, a lesion derived from a 3-year-old boy was studied by light microscopy, indirect immunofluorescence, using antibodies against basal lamina constituents and against interstitial matrix components, and electron microscopy. In addition, a rabbit antibody specific for bovine smooth-muscle myosin was used. The antibodies against the basal lamina components and fibronectin all showed an intense perimysial fluorescence that ensheathed and surrounded individual leiomyocytes. Anti-smooth-muscle myosin exhibited intense cytoplasmic fluorescence. Furthermore, electron microscopy showed fusiform cells with abundant myofilaments, dense bodies, and pericellular basal lamina as seen in smooth muscle. These studies suggest the probable origin of this hamartoma from pili arrector muscle and could be used as an adjunct in histopathological diagnosis.