Generalized Palisaded Neutrophilic and Granulomatous Dermatitis-a cutaneous manifestation of Chronic Myelomonocytic Leukemia? A Clinical, Histopathological and Molecular Study of Three Cases

Palisaded neutrophilic and granulomatous dermatitis (PNGD) is characterized by erythematous papules or plaques on trunk or limbs and is frequently associated with rheumatological, autoimmune or hematological malignancies. Histopathology shows interstitial granulomas composed of epitheloid histiocytes in the reticular dermis with surrounding foci of collagen degeneration and variable neutrophilic inflammation. We report three cases of generalized PNGD associated with chronic myelomonocytic leukemia (CMML), a myelodysplastic/myeloproliferative neoplasm, which may show a variety of cutaneous manifestations. SRSF2 P95 hotspot mutations, found in 40–50% of CMML cases, were retrospectively detected in skin and bone marrow (BM) biopsies of all three patients, in one of them already five years before CMML diagnosis. Generalized PNGD may represent a type of cutaneous manifestation of CMML. Since diagnosis of CMML is frequently difficult in cases with isolated persistent monocytosis and minimal dysplasia in the BM, patients with a generalized PNGD should be evaluated for the presence of hematological disorders including CMML, ideally supported by mutational analyses.