Pathology of  Giant Cell Collagenoma

Dr Sampurna Roy MD

Giant cell collagenoma was described for the first time by Rudolph et al in 1998.

It is a cutaneous fibrous neoplasm that usually affects young to middle-aged adults.

Despite its similar histological appearance with circumscribed storiform collagenoma, no association of Giant cell collagenoma with Cowden's syndrome has been described so far.

Gross: Presents as solitary slow-growing flesh-coloured nodules in young and middle-aged adults.

Microscopic feature: These lesions are characterized by sharply demarcated matrix consisting of coarse hyalinized collagen bundles arranged in a prominent storiform pattern and  separated by mucin-containing clefts. 

Admixed with the collagen matrix, there are two distinct cell populations.

(i) spindle-shaped mononuclear cells, and (ii) bizarre multinucleated giant cells.  

Atypical nuclei or mitotic figures are not present.

Immunohistochemistry:  Mononuclear cells expressed vimentin and actin HHF35. Multinucleated cells only expressed vimentin. 

The cells are negative for cytokeratin, desmin, S-100 protein, CD34, factor XIIIa, and the macrophage markers KP1, Mac 387.

Differential diagnosis: Storiform Collagenoma;Pleomorphic fibroma ; Dermatofibroma ; solitary myofibroma