sclerosing basal cell carcinoma
Wednesday 22 May 2013
The sclerosing category includes lesions which have also been referred to as fibrosing, scirrhous, desmoplastic and morpheic.
The uncommon ’field fire’ type with central fibrosis resulting from regression should not be included in this category. Up to 5% of all basal cell carcinomas are of the sclerosing type.
The tumor presents as an indurated, pale plaque with a slightly shiny surface and clinically indistinct margins. There are narrow elongated strands and small islands of tumor cells embedded in a dense fibrous stroma.
If the stroma has dense, eosinophilic areas resembling a keloid, then the term ’morpheic’ has traditionally been used, although at other times this term has been used interchangeably with ’sclerosing’.
The term ’keloidal’ has been applied to basal cell carcinomas with thick sclerotic keloidal collagen bundles in the stroma.
A selectively enhanced procollagen gene expression has been found in the sclerosing variant. Also, large defects have been found in the basal lamina that surrounds the tumor nests. Smooth muscle (x‑actin and myosin) are often present in the stroma.