Unilateral granuloma annulare in association with pyoderma gangrenosum and chronic lymphocytic leukemia.

Granuloma annulare (GA) is a fairly common inflammatory skin condition with a range of clinical subtypes. We describe an unusual case of unilateral GA confined to the thigh on a previously amputated limb. A man in his 80s with a past medical history of below-knee amputation of the left leg owing to severe leg ulcers from pyoderma gangrenosum, chronic lymphocytic leukemia, and dyslipidemia developed a slowly spreading eruption on the distal stump spreading proximally. On physical examination, he had numerous non-scaly violaceous papules and annular plaques from the stump to the lateral, medial, and anterior thigh. Histology confirmed a diagnosis of GA. The extensive, chronic lesions make this presentation of GA very unusual in that it shares features of both localized and generalized forms. Moreover, the temporal and spatial association with pyoderma gangrenosum is unique and may reflect a related inflammatory pathway.