prostatic basal cell carcinoma

Definition: Prostate basal cell carcinoma is a neoplasm composed of prostatic basal cells. It is believed that a subset of basal cells are prostatic epithelial stem cells, which can give rise to a spectrum of proliferative lesions ranging from basal cell hyperplasia to basal cell carcinoma.

Clinical features

Patients are generally elderly, presenting with urinary obstruction with TURP being the most common tissue source of diagnosis. The youngest reported case was 28 years old.

Histopathology

Some tumours resemble its namesake in the skin, comprising large basaloid nests with peripheral palisading and necrosis.

Other patterns have histologic similarity to florid basal cell hyperplasia or the adenoid basal cell pattern of basal cell hyperplasia (the latter pattern of cancer occasionally referred to as adenoid cyst ic carcinoma).

Histologic criteria for malignancy that distinguish it from basal cell hyperplasia include an infiltrative pattern, extraprostatic extension, perineural invasion, necrosis and stromal desmoplasia.

Basal cell carcinoma shows immunoreactivity for keratin 34βE12, confirming its relationship with prostatic basal cells. S-100 staining is described as weak to intensely positive in about 50% of tumour cells, raising the possibility of myoepithelial differentiation; but there is no corroborative antismooth muscle actin (HHF35) reactivity 954 nor ultrastructural evidence of a myoepithelial nature.

Distinction from basal cell hyperplasia with a pseudoinfiltrative pattern or prominent nucleoli can be difficult; basal cell carcinoma shows strong
BCL2 positivity and high Ki-67 indices as compared to basal cell hyperplasia.

Prognosis

The biologic behaviour and treatment of basal cell carcinoma is not well elucidated in view of the few cases with mostly short follow-up.

Local extra-prostatic extension may be seen, along with distant metastases.

A benign morphologic counterpart to basal cell carcinoma (basal cell adenoma) has been proposed, although it should be considered as florid nodular basal cell hyperplasia.

Basaloid carcinoma of the prostate gland: histogenesis and review of the literature.

References

 Denholm SW, Webb JN, Howard GC, Chisholm GD. Histopathology. 1992 Feb;20(2):151-5. PMID: 1559669