Type VII collagen is a component of cylindroma basement membrane zone

Cylindroma basement membranes (BMs) were studied by electron microscopy and immunofluorescence with antibodies to Types IV and VII collagen in order to correlate the ultrastructure with the biochemical characteristics. Type IV collagen served as a marker for lamina densa structures and Type VII collagen for the anchoring fibrils. Ultrastructurally, the cylindroma BMs were composed of a wide band of BM-like material in which numerous anchoring fibrils were embedded. The BMs surrounding the tumor cell clusters and nodules of BM-like material entrapped within the tumor cell islands stained positively for both Types IV and VII collagen. We conclude, that anchoring fibrils are a major component of cylindroma BM zone. A trichoepithelioma investigated as control showed a BM similar to the one found at the dermoepidermal junction, i.e. a BM distinctly different from the one of cylindroma. The trichoepithelioma BMs and nodules of BM-like material included within the tumor also stained positively for both Type IV and VII collagen.