DP22 Cutaneous lymphoid hyperplasia: clinicopathological correlation and a therapeutic option

Cutaneous reactive lymphoid hyperplasia, also known as cutaneous pseudolymphoma, is an uncommon entity in which there are skin lesions that histologically, and sometimes clinically, mimic cutaneous lymphoma but are not, both morphologically and immunohistochemically. Correlating clinical, pathological, immunohistochemical and, occasionally, molecular findings is essential for the diagnosis (Romero-Perez D, Blanes Martinez M, Encabo-Duran B. Pseudolinfomas cutaneous. Actas Dermosifiliogr 2016; 107:640–51). Although the majority of cases can be regarded as idiopathic, certain infections and inflammatory conditions can precipitate cutaneous reactive lymphoid hyperplasia, examples of which include Borrelia infection, insect bite reactions and folliculitis (Mitteldorf, C, Kempf, W. Cutaneous pseudolymphoma – a review on the spectrum and a proposal for a new classification. J Cutan Pathol 2020; 47:76–97). The first case was an 18-year-old woman who presented with deep dermal and subcutaneous nodules for the last 5 years that started on her limbs and were slightly itchy. The nodules were firm and deep, with minimal surface changes (hyperpigmentation and adherent scale) but did not ulcerate. She also had nodules involving her buccal mucosa, inner lips and soft tissue in the nasal bridge and a couple of deep nodules on the cheeks. Pathological examination showed a dense lymphocytic infiltrate with plasma cells admixed with other inflammatory cells involving the deep dermis with an extension to the dermal/subcutaneous junction. The pathological picture was in the spectrum of deep tumid lupus/lupus panniculitis overlap and cutaneous lymphoid hyperplasia. Immunohistochemical stains showed a mixture of inflammatory cells with CD3+ and CD20+ cells. Lip mucosal biopsy showed florid reactive lymphoid follicular hyperplasia. Her condition was resistant to multiple systemic treatments. Eventually, she underwent treatment with rituximab and had satisfactory results. The second patient is an elderly female who had multiple erythematous papules, plaques and nodules on her face. Pathological examination showed a dense dermal lymphocytic infiltrate with periadnexal predilection and reactive follicles that also were highlighted by CD20, with Bcl2 and CD3+ cells around germinal centres. She was diagnosed as having cutaneous reactive lymphoid hyperplasia. Topical calcineurin inhibitors were initiated, with a good response. In conclusion, this paper highlights the term cutaneous pse