Dermal dendrocytes are decreased in collagenomas

Dermal dendrocytes comprise a subset of spindle-shaped cells which normally reside in the dermis. While they appear to play some role in the reticuloendothelial system, their exact functions have not been completely elucidated. In addition to their purported immunologic functions, it has been suggested that dermal dendrocytes may play an inhibitory role in the regulation of dermal collagen synthesis. We examined 7 collagenomas with antibodies directed against factor XIIIa (FXIIIa) in order to test the hypothesis that dermal dendrocytes were focally diminished in these hamartomatous overgrowths of collagen. In all cases, there was a marked diminution in the number of FXIIIa-positive cells in the lesional dermis when compared to the surrounding dermis. Our data support the hypothesis that dermal dendrocytes may be involved in regulation of collagen synthesis.