Blackrock Clinic, Ireland
Clare Byrne is a General Medical Registrars at Blackrock Clinic. Byrne studied her MBChB at University of Aberdeen; BSc at University College London and; is currently pursuing her MSc in Skin Ageing & Aesthetic Medicine at University of Manchester. Jane McManus completed Medical Degree at Trinity College, Dublin and MSc in Public Health.
Granuloma Annulare (GA) is a benign skin condition of unknown aetiology which presents with papules, often in an annular distribution. GA can mimic or occur in association with other conditions including morphoea. Histologically both show vascular damage, altered collagen, and lympho-histiocytic infiltrates. While GA has inflammation and fragmented collagen bundles, necrobiosis and granulomatous formation with mucin distribution and multi-nucleated giant cells, morphoea demonstrates dermal fibroblast excess. We outline an unusual presentation of GA initially thought to be morphoea. While rare, there are reported cases of both occurring together and of GA presenting with a similar uncharacteristic appearance. Clinical correlation is essential to establish a diagnosis given the overlap in histopathology. A 43-year-old woman was presented with a five-week history of painful swelling and discoloration of the left forearm. Negative Doppler’s excluded thrombosis. She was treated with flucloxacillin for cellulitis but returned one month later with worsening symptoms including morning stiffness in the wrists, small joints of the hands and bilateral forearm swelling. Rheumatology review identified swelling and tenderness over the left wrist and first MCP-joint, knees, hips and forearms. There was a dusky erythematous rash and sclerodactyly with thickened skin over the entire left forearm. ANA was weakly positive. The arthralgia raised concerns that this might represent early manifestation of an autoimmune disease. Morphea was provisionally diagnosed. Following exclusion of malignancies, dermatology agreed with this diagnosis. However, biopsies were consistent with GA despite the atypical presentation. She responded to methotrexate, deltacortril and Elocon cream.