fibrous umbilical polyp
Thursday 17 June 2010
The fibrous umbilical polyp appears to be a distinctive lesion of early childhood with an uncertain pathogenesis.
It has a marked predilection for boys. A series of 19 cases from one institution suggests that it is not rare. They ranged in size from 0.4 to 1.2 cm in diameter.
The fibrous umbilical polyp is a dome-shaped lesion with a stromal proliferation of moderately cellular fibrous tissue without significant inflammation.
Fibroblastic cells are plump to elongate with abundant pale pink cytoplasm. Some cells show enlarged stellate nuclei or a ganglion cell appearance. Collagen is sparse to moderate in amount.
The overlying epidermis shows a loss of rete ridges and basket-weave hyperkeratosis. Some cases show focal staining for muscle-specific actin and desmin but no staining for cytokeratin, CD34, S100, or epithelial membrane antigen.