Mondo Description Interstitial granulomatous dermatitis with arthritis is a rare rheumatologic disease characterized by the occurrence of inflammatory arthritis in association with large, erythematous, symmetrical cutaneous lesions (ranging from typical, but infrequent, cord-like lesions on the flanks to more common violaceous plaques on the trunk and limbs) featuring a typical histologic infiltrate mainly constituted of histiocytes.