Pilar sheath acanthoma is a
rare, benign follicular hamartoma described first in 1978 by Mehregan
Clinical presentation: Clinically resembles a comedo
characterized by a central
pore- like opening plugged with keratin. Lesion is 5-10mm in diameter,
occuring almost always on the upper lip. Cases have been reported
on other areas of the
head and face.
Dermatopathology Case 86
-Central cystically dilated follicle containing keratinous material;
-follicle opening to surface;
-buds of squamous epithelium radiate from the
-tumour lobules are composed of outer root sheath
-abundant glycogen in some of the tumour cells ;
-epidermoid keratinisation ;
-lesion extends into the dermis or
occasionally into the subcutaneous fat.
Differential diagnosis: -
Dilated pore (small finger-like projections extending into the
dermis) ; 2.Trichofolliculoma (secondary hair follicles radiate from the wall of the primary
follicle, an outer root sheath, inner root sheath and trichohyaline
granules are noted in the secondary follicles) ; 3.Poroma .