Nerve involvement in granuloma annulare

Background: Nerve involvement developed in a patientwith granuloma annulare, as evidenced by a perineural infiltrate of histiocytes in the dermis. The histopathologic patternwas suggestive of leprosy. Nomycobacteriawere observed, and neurologic testing was normal. Objective: To determine whether inflammation of the nerves or perineural tissue is common in granuloma annulare, we studied the cutaneous nerves in skin biopsy specimens from 14 patients with granuloma annulare. Methods: Sections were stainedwith hematoxylin-eosin to highlight inflammatory cells andwith S-100 to identify cutaneous nerves. Results: No inflammation around nerves was found in 12 specimens, abutting granulomatous inflammation was found in 1 specimen, and enveloping granulomatous inflammation was found in 1 specimen. No nerves were infiltrated by inflammatory cells. Conclusion: Perineural granulomatous inflammation resembling the perineural infiltrate of leprosy appears to be an uncommon characteristic of granuloma annulare. Clinical correlation and acid-fast stains can assist in establishing the correct diagnosis.