DP20 The rash that would not settle: a clinicopathological journey to Kimura disease

Abstract

Kimura disease is a rare, chronic inflammatory disorder characterized by eosinophil-rich infiltrates and reactive lymphoid hyperplasia. It predominantly affects Asian populations; it is uncommon in the UK and therefore under-recognized. Multisystem involvement and overlapping clinicopathological features can lead to diagnostic delay. We present an unusual and diagnostically challenging case of Kimura disease with cutaneous, orbital and soft-tissue manifestations, highlighting the importance of clinicopathological correlation. A 42-year-old woman presented in November 2022 with an intermittent erythematous rash affecting the limbs, later becoming persistent. Initial skin biopsies demonstrated an interstitial histiocytic infiltrate with numerous eosinophils. In April 2023, she developed bilateral periorbital swelling with fatigue and headaches, prompting ophthalmological assessment. IgG4-related disease was considered; however, lacrimal gland biopsy showed reactive lymphoid hyperplasia without increased IgG4-positive plasma cells, and serum IgG4 levels were normal. Peripheral blood eosinophilia was present. Autoimmune serology, connective-tissue disease screening and imaging were nondiagnostic. Haematological assessment excluded lymphoma, and rheumatological review did not identify a unifying diagnosis. Symptoms showed partial, transient responses to systemic corticosteroids and immunosuppressive agents, with relapse on treatment withdrawal. Subsequently, a subcutaneous nodule that developed on the left upper arm was excised. Histology of the soft-tissue nodule demonstrated classical features of Kimura disease, with reactive lymphoid follicles containing germinal centres and a dense eosinophilic infiltrate with eosinophilic micro­abscesses. Multidisciplinary review concluded that Kimura disease provided a unifying diagnosis. Bilateral lacrimal gland involvement, although uncommon, is well described in Kimura disease, and reactive lymphoid follicles supported this diagnosis despite absence of eosinophils. The relapsing cutaneous eruption, showing interstitial granulomatous dermatitis, was considered secondary to immune dysregulation associated with Kimura disease. The patient is currently stable on mycophenolate mofetil and topical clobetasol propionate. This case highlights the diagnostic journey of rare inflammatory disorders involving multiple systems and underscores the central role of histopathology and multidisciplinary collaboration.