CD34-reactive trichodiscoma.
BACKGROUND
Trichodiscomas are rare hamartomas of the dermal portion of the hair disc, a specialized component of the perifollicular mesenchyme. They are usually found as asymptomatic multiple skin-colored papules on the face and extremities and may have an autosomal dominant inheritance pattern. However, a solitary variant has been described.


METHODS
A 78-year-old woman presented with a single, non-pigmented, firm papule on the left tip of the nose, measuring 3.5 mm in diameter.


RESULTS
The histological examination revealed the previously described features of a trichodiscoma. The immunohistochemical analysis showed strong immunoreactivity for CD34 in the spindle cell component. Spindle cells were negative for S-100, HMB-45, Melan-A, EMA, neurofilament, desmin, and Factor XIIIa by immunohistochemistry.


CONCLUSIONS
We report strong reactivity for CD34 in the spindle cell component of a trichodiscoma. We suggest that this lesion be considered in the differential diagnosis of any CD34+ dermal spindle cell proliferation, in which an adjacent epithelial component cannot be entirely excluded.
Chartier
Molly
M
Department of Dermatology, University of Connecticut Health Center, Dowling South, 263 Farmington Avenue, Farmington, CT 06030, USA.
Reed
Michael L
ML
Mandavilli
Srinivas
S
Fung
Maxwell
M
Grant-Kels
Jane M
JM
Murphy
Michael
M
D000368:Aged; D018952:Antigens, CD34 / Q000378:metabolism*; D003937:Diagnosis, Differential; D005148:Facial Dermatoses / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006201:Hair Diseases / Q000378:metabolism* / Q000473:pathology; D006222:Hamartoma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D009668:Nose Diseases / Q000378:metabolism* / Q000473:pathology
D018952:Antigens, CD34