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Nuchal fibroma presenting as two posterior neck masses

Dear Editor, Nuchal fibroma (NF), first described in 1988 by Enzinger and Weiss, is a rare, benign fibrous proliferation characterized by hypocellular dense collagens in the dermis and subcutaneous fat layer. It usually develops in the posterior neck as a solitary soft tissue mass. We report an unusual case of a NF presenting as two masses on the posterior neck in a 35-year-old Korean woman. The patient presented to our department with a 17-year history of two, dome-shaped masses on the posterior neck. The masses were firm, fixed, skin-colored nodules, measuring 3.5 cm × 5 cm and 4 cm × 5 cm, respectively (Fig. 1). Neither of the lesions undermined the epidermis, and the textures and the degree of hardness were nearly same. These lesions were asymptomatic, with the exception of a somewhat limited neck motion and slight loss of sensation. The patient had no significant medical history and no history of trauma to the area. Laboratory findings were all normal. Under the clinical diagnosis of lipoma, an incisional biopsy was performed from the left neck mass. An histopathological examination revealed dense hypocellular fibrosis throughout the dermis and the subcutaneous fat layer. Collagen fibers were thick and haphazardly arranged. Some areas of subcutaneous fat were replaced by collagen and mature fat lobules, eccrine glands and nerve fibers were entrapped by collagen fibers (not shown). On alcian blue stain, mucin was not demonstrated (not shown). The diagnosis of NF was made based on the location and the characteristic histopathological findings of masses. Nuchal fibroma occurs more frequently in middleaged males than females, and it may even affect extranuchal locations. The most common extranuchal sites are the back or interscapular regions, but the other affected sites include the shoulder, face, forearm, anterior neck, knee and trunk. Usually, NF presents as a single lesion and only two patients have been reported to have two distinct lesions. In both cases, one lesion was in the nuchal area and the other in the extranuchal location. However, in our patient, the two distinct lesions were both in the nuchal area, different from the previously reported cases. The pathogenesis of NF remains unknown, but some cases of NF have been associated with trauma, diabetes and, rarely, Gardner’s syndrome. Studies have shown that mechanical stress activates the production of collagen and growth factors in fibroblasts, such as transforming growth factor-β, platelet-derived growth factor, basic fibroblast growth factor, and connective tissue growth factor. In addition, NF was reported to be associated with diabetes in up to 44% of the patients in one study suggesting that it may be a sclerotic process associated with diabetes mellitus. In Gardner’s syndrome NF and Gardner-associated fibroma (GAF) resemble one another histologically; thus, when NF occurs in multiple sites, unusual locations, or children one should consider the possibility of GAF prior to NF. However, in our patient as well as in previously reported patients who had two distinct lesions of NF, there were no associations with these underlying etiologies. Macroscopically, NF is poorly circumscribed, subcutaneous or dermal in location. It consists of dense, haphazardly arranged bundles of collagens with