Erythema nodosum and sarcoid granulomas - letting the cat out of the bag.

A 41-year-old woman presented with a violaceous papule on the dorsum of the hand, large ipsilateral axillary lymphadenopathy, and tender, erythematous, subcutaneous nodules on the legs. Accompanying signs included fever, ankle swelling, and bilateral red eye. She recalled having a previous exposure to kittens one month before and had a positive family history for sarcoidosis. Histological examination of the hand lesion showed sarcoidal granulomas with positive Bartonella henselae DNA, whereas a biopsy done on the leg nodules was compatible with erythema nodosum. Cat scratch disease (CSD) typically presents as a tender regional lymphadenopathy preceded by an inoculation papule with spontaneous resolution occurring between 8-16 weeks. Cutaneous manifestations of CSD are rare, with erythema nodosum accompanying only 0.6% of cases. Although speculative, the background of a positive family history for sarcoidosis may explain the atypical presentation of this case, with red eye, persistent arthralgia, and associated sarcoidal granulomas.