DP21 Thymoma and the skin: manifestations of multiorgan autoimmunity

Abstract

Abstract We present three patients who developed distinct cutaneous manifestations of thymoma: a rare mediastinal tumour. A 25-year-old man was treated for myasthenic crisis. Past medical history included thymectomy in 2016. Admission imaging confirmed recurrence of thymoma. He developed a red–brown macular rash affecting the trunk, back and thighs. Biopsy showed a florid lichenoid dermatitis consistent with graft-versus-host disease (GVHD). After resolution with steroids and mycophenolate mofetil, he subsequently developed a Stevens–Johnson syndrome/toxic epidermal necrolysis-like eruption with erythroderma and epidermal loss. Unfortunately, he developed multiorgan failure and died shortly afterward. A 43-year-old man presented to the emergency dermatology clinic with a 4-month history of a blistering rash affecting the chest and limbs. His previous medical history was significant for thymoma in 2008 and a recurrence in 2013. Skin biopsy demonstrated changes suggestive of bullous pemphigoid, and repeat computed tomography confirmed the recurrence of thymoma. Enzyme-linked immunosorbent assay testing was positive for bullous pemphigoid 180. He has responded well to prednisolone and doxycycline. A 51-year-old woman was reviewed in 2020 and 2021 with pruritic hyperpigmented patches affecting the face, trunk and limbs. Her past medical history included several relapses of thymoma with occurrence in 2002 and relapses in 2007, 2008, 2011, 2015 and 2021. Skin biopsy in June 2021 showed features of cutaneous GVHD. She received ruxolitinib and tapering steroids for thymoma-associated multiorgan autoimmunity (TAMA)-like GVHD and has had a remarkable improvement in her skin disease. Thymoma is described as a rare neoplasm, and up to 34% of thymomas are thought to be accompanied by symptoms of autoimmunity. The most frequently described syndromes include myasthenia gravis, pure red blood cell aplasia and hypogammaglobulinaemia. Other reported presentations include panencephalitis, enterocolitis and autoimmune hepatitis. Thymoma and cutaneous autoimmune presentations have been previously described, often in association with two rare syndromes: TAMA and paraneoplastic autoimmune multiorgan syndrome (PAMS). Both conditions demonstrate variability in clinical phenotype, driven by the activation of humoral and cellular immune responses. Clinically, patients may present with a spectrum of skin disease, including GVHD-like exanthems, lichen planus-like disease and pemphigus-like and pemphigoid-like lesions. Our case series demonstrates the heterogeneous cutaneous manifestations of thymoma-induced autoimmunity. We also describe two extremely rare phenomena accompanying thymomas: TAMA and PAMS. We also suggest that there is much crossover between these syndromes and previous definitions may require further review. This case series also highlights the importance of the wider multidisciplinary team in managing these patients and the complexities of their disease.