Nuchal fibrocartilaginous pseudotumor: a distinctive soft-tissue lesion associated with prior neck injury.

Soft-tissue tumors with a predilection to involve the head and neck region include spindle cell lipoma, pleomorphic lipoma, and nuchal fibroma. We have recently studied three patients with distinctive soft-tissue fibrocartilaginous masses in the posterior aspect of the base of the neck, at the junction of the nuchal ligament and the deep cervical fascia. Two of the patients were women (ages 37 and 40) and one a man (age 53). All three had sustained neck injuries in automobile accidents in the past (27 years, 20 years, and 2 months before surgery, respectively). Each patient presented with a soft-tissue nodule overlying the spinous process of one of the lower cervical vertebrae. Two were painful. Computed tomography and magnetic resonance imaging performed in two patients showed focal thickening of the ligamentum nuchae at the C4-5 and C5-6 levels. All three masses were completely excised. They ranged in size from 1.0 to 1.5 cm. The three lesions were histologically identical, and each consisted of a poorly defined, moderately cellular fibrocartilage nodule located within the nuchal ligament at its junction with the deep cervical fascia. Atypia or mitotic activity was not present. The ligamentous tissue adjacent to the mass was irregular and degenerated. None of the masses have recurred in follow-up periods of 3 to 6 months, and all patients are currently asymptomatic. The lesion we describe is a distinctive soft-tissue pseudotumor that occurs in the mid-line of the lower cervical spine within the nuchal ligament. It is likely non-neoplastic and probably develops as a reaction to soft-tissue injury, in an analogous manner to fibrocartilage metaplasia seen in degenerated tendoligamentous structures. We propose the term "nuchal fibrocartilaginous pseudotumor" for these lesions.