We describe an unusual lesion that represents an uncommon but important element in the differential diagnosis of subcutaneous scalp nodules in a child.
A 1-year-old boy presented with two clusters of subcutaneous scalp nodules. The lesions increased in size and number. Computed tomography showed no changes in underlying bone. Findings on magnetic resonance imaging were nonspecific. Serologic and clinical evaluation showed no evidence of rheumatic disease. Complete excision of the nodules, together with adjacent fascia and galea, was performed. Histopathologic examination showed the lesions to be palisading granulomas; given the absence of rheumatic disease, these represented deep granuloma annulare, a benign condition. No recurrence has been observed in our patient.
While we chose total excision because of preoperative concerns about a possible malignant tumor, some other authors have suggested that surgery be limited to confirmatory biopsy when a benign lesion such as palisading granuloma is strongly suspected.