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Published on: February 8, 2019
Nerve involvement in granuloma annulare
Michelle Longmire1, David J DiCaudo, Mark V Dahl
1Department of Dermatology, Mayo Clinic, Scottsdale, AZ 85259, USA.
Background:
Nerve involvement developed in a patient with granuloma annulare, as evidenced by a perineural infiltrate of histiocytes in the dermis. The histopathologic pattern was suggestive of leprosy. No mycobacteria were 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 stained with hematoxylin-eosin to highlight inflammatory cells and with 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.
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