Pilar sheath acanthoma is a
rare, benign follicular hamartoma described first in 1978 by Mehregan
and Brownstein.
Clinical presentation: Clinically resembles a comedo
and is
characterized by a central
pore- like opening plugged with keratin. Lesion is 5-10mm in diameter,
Site:
Solitary lesion
occuring almost always on the upper lip. Cases have been reported
on other areas of the
head and face.
Microscopic features:
Central cystically dilated follicle containing keratinous material;
follicle opening to surface; buds of squamous epithelium radiate from the
central pore; tumour lobules are composed of outer root sheath
epithelium; abundant glycogen in some of the tumour cells ;
epidermoid keratinisation ; lesion extends into the dermis or
occasionally into the subcutaneous fat.
Differential diagnosis: -
1.
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 .
Image link(Dr
Weems)
;
Case link |