Case Report

A 56-year-old female presented with a slightly raised nodule on the lower lip measuring 0.7 x 0.7 cm. This lesion was noted by the patient for about a month. There was no history of trauma or previous biopsy at this site. An excisional biopsy was performed.

Microscopically, the lesion showed a dermal benign fibrotic and hyalinized nodule with overlying normal epidermis (Figure 1A). The hyalinized lesion was composed of acellular fibrocollagenous tissue with few stellate fibroblastic cells containing small dark splindle-shaped nuclei (Figure 1B). The stellate fibroblastic cells were strongly positive for CD34 (Figure 2B) and Vimentin (Figure 2B) but were negative for S-100 protein, SMA, and CD31.

Figure 1

Figure 1A: Normal epidermis, dermal nodule.

Figure 2

Figure 1B: Dermal tumor

Figure 3

Figure 2A: CD34 positive.

Figure 4

Figure 2B: Vimentin positive

Comment

Fibromas occur in any area of the oral mucosa but are most often located on the palate, tongue, cheek, or lip. They typically appear as pink or white elevated submucosal nodules. When such lesions are traumatized, they may appear reddish or blue. They tend to have a smooth surface and may be round, oval or elliptical in shape. The size of a fibroma can vary from a few millimeters to about 2 centimeters. A CD34-positive fibroma is a rare entity. Such a tumor may cause a diagnostic confusion with other CD34-positive cutaneous tumors including sclerotic fibroma [₁], solitary fibrous tumor, eruptive CD34-postive fibroma [₂], pleomorpic fibroma [₃], dermatofibrosarcoma protuberans [₄], and Kaposi's sarcoma. Most of these lesions can be excluded by the clinical finding, histologic appearance and results of immunohistochemical stains. CD34-positive fibroma is considered a benign, non-recurrent dermal neoplasm, a subset of cutaneous or mucosal fibromas.

Correspondence to

Deba P Sarma, M.D. Department of Pathology Creighton University Medical School Omaha, NE 68131 debasarma@creighton.edu