of the follicular infundibulum (TFI) is a simple follicular
acanthoma with characteristic histopathologic features.
(1) solitary tumours, (2) eruptive tumours, (3) TFI - associated with
other lesions of Cowden's disease, (4) TFI- associated with a single
tumour such as nevus sebaceus, and (5) TFI-like epidermal changes.
Clinically presents as
a small asymptomatic, smooth or slightly keratotic papule or plaque.
Sites: Head and
neck or upper chest.
Symmetrical tumour with plate-like growth
pattern of the squamous cells ( similar to isthmic or outer root
sheath epithelium) parallel to the surface epithelium ; Multiple
attachments to the epidermis ; Basal cell palisade ; Acanthotic
epithelium eosinophilic and pale staining than the overlying epidermis ;
Small ducts and microcavities with keratin in the lesion; PAS- positive
Inverted follicular keratoses ; trichilemmomas ; Plaque-like seborrheic keratosis
; Superficial basal cell carcinoma; Multiple infundibular
tumors of the head and neck.