Subungual Myxoid Pleomorphic Fibroma

Abstract

The authors report an example of pleomorphic fibroma in a unique site: the subungual space of the thumb. A 54-year-old man presented with paronychia and markedly thickened hyperkeratotic nail. The nail plate was removed, and an exophytic, red, friable, granulation tissue-like lesion was revealed subungually. The lesion was diagnosed clinically as pyogenic granuloma. Excisional biopsy was performed. Histologically, the lesion showed a hypocellular fibroma with myxoid areas and dilated blood vessels. Interspersed with ordinary appearing fibroblasts, there were bizarre, atypical fibroblasts with hyperchromatic and large, pleomorphic nuclei and multinucleated floret-like giant cells. These atypical cells showed strong immunoreactivity with antibodies against CD34 and vimentin. Occasional positivity was noted with factor XIIIa and alpha-1-antichymotrypsin, whereas no reactivity occurred with alpha-1-antitrypsin, actin, or S-100 protein. The entity of pleomorphic fibroma has been reported in many body sites; however, this is the first case to be reported in the subungual space.

Multinucleated giant cells from fibroblast cultures

“…One phenotypic alteration that is not widely acknowledged, but possible is fibroblast multinucleation [6–8]. Additionally, several other multinucleated giant cells including foreign body giant cells (FBGCs), Langhans’ cells, and osteoclasts, all commonly derived from a macrophage cell origin are known [10].…”

“…Previous studies have identified multinucleated cells in vivo ostensibly of fibroblast origin [6, 7], one describing cells appearing as “bizarre, atypical fibroblasts with hyperchromatic and large, pleomorphic nuclei and multinucleated floret-like giant cells”[8]. Several studies describe the presence of multinucleated fibroblasts in vitro [18–21] and in vivo in pathologies such as fibrosis and cancer and in aged tissue [1–8].…”

“…Several studies describe the presence of multinucleated fibroblasts in vitro [18–21] and in vivo in pathologies such as fibrosis and cancer and in aged tissue [1–8]. However, whether these cells multinucleate in vitro and in vivo via fusion similar to FBGCs [11] or through nuclear division without cytokinesis [18] is unclear.…”

Macrophage and Multinucleated Giant Cell Classification

“…These balloon cells (not to be confused with multinucleated melanocytes) have been suggested to be of either neuronal or glial origin [159]. Floret giant cells have been observed in various neoplasms including multinucleate cell angiohistiocytoma, pleomorphic lipoma, giant cell fibroblastoma, giant cell collagenoma [160], neurofibroma [161], pleomorphic fibroma [162], and dermatofibroma [163]. The name "floret" reflects the unique nuclear arrangement around the periphery of the cell, similar to petals on a flower.…”

Benign Subungual Tumors

“…32 To date, 2 cases of subungual pleomorphic fibromas have been reported. 32,33 Hsieh et al 32 reported a 66-year-old woman who presented with a 40-year history of a nail deformity of …”