Nuchal fibrocartilaginous pseudotumor: a clinicopathologic study of five cases and review of the literature.

The clinicopathologic features of five cases of a fibrocartilaginous mass developing in the nuchal ligament, the nuchal fibrocartilaginous pseudotumor, are described. Only six examples of this lesion were previously reported in the English-language medical literature. The lesions clinically manifested in five adults (3 women, 2 men) ranging in age from 22 to 46 years (mean, 37 yr). The process presented as a nodular mass that was asymptomatic in three patients and accompanied by vague neck pain or stiffness in the remaining two. Three patients related a history of head and neck trauma that preceded the discovery of the tumor. All of the tumors were situated in the deep soft tissue overlying the posterior aspect of the lower cervical vertebrae. The five patients were managed by complete local excision. The tumors measured 1.3 to 3.0 cm. in greatest dimension (mean, 2.5 cm.). Microscopically, the lesion consisted of a poorly delineated, nodular proliferation of moderately cellular fibrocartilaginous tissue arising within the substance of the nuchal ligament and extending into the surrounding soft tissues. No cytologic atypia or mitotic activity was identified. Follow-up data from four of the cases in this study (range, 10-324 mo) and four previously reported examples with follow-up (range, 3-12 mo) show no evidence of recurrent or persistent disease after simple excision. The nuchal fibrocartilaginous pseudotumor is a benign lesion caused by fibrocartilaginous metaplasia of the lower portion of the nuchal ligament, probably as a result of localized trauma or chronic mechanical stress.