Regional lymphomatoid papulosis (LyP) accounts for 2-27% of all LyP cases. Several localized dermatoses have been reported in association with Becker's melanosis (BM), e.g. acneiform lesions or lichen planus. Here, we report on regional LyP confined to the area of BM. A 56-year-old man presented with a 1-year history of a steadily increasing number of multiple pruritic red papules developing on the area of BM, which had occurred on his left shoulder during puberty. Histopathological analysis was consistent with regional LyP. Potent topical steroids followed by oral doxycycline did not achieve improvement, while long-term oral bexarotene treatment ameliorated the skin condition. Recently, the proposed entity of ‘persistent agmination of LyP' (PALP) has extended the clinicopathological observations of regional LyP. Since PALP remains controversial, a unifying concept of localized LyP and PALP will be discussed.

Summary Sweet syndrome (acute febrile neutrophilic dermatosis) is characterized by a dramatic onset of high fever, neutrophilia and typical skin lesions. About 20 % of patients have an associated malignancy, most commonly hematologic diseases. Chronic and paucisymptomatic manifestations of Sweet syndrome may be misdiagnosed or misinterpreted as harmless, resulting in delayed diagnosis. “Atypical” manifestations are especially suspicious for associated malignancies. This is demonstrated by a 39‐year old patient with chronic and afebrile disease who was referred to our clinic only after symptoms had persisted for several months. By that point, an underlying nodular lymphocyte predominant Hodgkin's lymphoma had already reached an advanced stage. Skin biopsies revealed dermal infiltrates of histiocytoid cells of myelogenous origin, supporting a diagnosis of histiocytoid Sweet syndrome. Specific cutaneous infiltrates associated with myelogenous leukemia were ruled out.

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