Atypical Nuchal-Type Fibromas: A Rare Presentation of the Soft Tissue Tumor in the Bilateral Lower Extremities.

Nuchal-type fibromas (NTFs) are rare, benign tumors that predominantly originate in the posterior neck and often arise due to repetitive mechanical use. They are more common in males than females. Clinically, NTFs present as slow-growing, painless masses that are firm to the touch and immobile. The masses are typically not accompanied by other symptoms of erythema, warmth, or ulcerations as they are non-inflammatory in nature, with the possibility of tenderness in later stages of growth as nerves become entrapped in the tumor. Patients may present with cosmetic concerns and focal discomfort depending on the location and size of the mass. Extra-nuchal sites are uncommon, with locations reported in the literature including the upper back, shoulder, and face, with only one case reported where an NTF was found unilaterally on the ankle. We present a rare case of a 48-year-old male with bilateral masses in the ankle extensor retinacula, consistent with nuchal-type fibromas determined by histopathology. To our knowledge, our patient's presentation of bilateral extra-nuchal NTFs of the lower extremity is among the first to be reported in the literature.