FIBROUS HISTIOCYTOMA OF SKIN WITH FOCAL OSSIFICATION AND PROMINENT GIANT CELLS, SOME OF WHICH ARE OSTEOCLAST-LIKE
(Giant Cell Granuloma of Skin with Ossification)
There is an oral lesion known as peripheral giant cell granuloma or giant cell epulis that is thought to represent a reparative or reactive process. Ossification can be present, and such lesions can, uncommonly, recur. Such lesions have a prominent fibrovascular background containing giant cells, occasionally of osteoclastic type.  The lesion that is presented here so closely resembles the oral lesion that I thought I was dealing with such an oral lesion before I noticed the location (ear) on the pathology request form.

Although ossification and/or osteoclast-like giant cells have been reported in dermatofibromasrefs. 1 & 2, the current lesion has architectural peculiarities unlike a dermatofibroma. The most dense collagen bundles are formed in the base of the lesion, and these collagen bundles arborize above the base. It is near the base that the ossification occurs. Cellular fibrovascular areas that contain numerous giant cells are between the collagen bundles above this zone, and the lesion becomes less cellular towards the periphery. In this particular case, the surface is eroded and lined by ordinary granulation tissue.

Cases published as fibro-osseous lesions of the external auditory canal ref. 3 are scantily illustrated, so any relationship to the current lesion is problematical.

I  recommend either of the terms given in the title but would be open to suggestions.


This polypoid mass is from the conchal bowl of the ear of a 49 year old male. There was no attachment to bone clinically, but an x-ray was not done.
 
Direct scan of slide. This polypoid lesion was amputated through the base. Much of the surface is eroded and replaced by granulation tissue. . Mitoses (not illustrated) are present, but none are abnormal.

 
 Medium power view of the area in the black rectangle.
An osteoclast-like giant cell (OGC) and osteoid (OST) are illustrated.
 Medium power view of osteoclast-like giant cells.
Medium power view from an area just above the black rectangle.

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