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Lymphomatoid hypersensitivity reaction to levofloxacin during autologous stem cell transplantation: a potential diagnostic pitfall in patients treated for lymphoma or leukemia

Drug‐associated cutaneous lymphomatoid hypersensitivity reactions are rare eruptions that can clinically and microscopically mimic a bona fide lymphomatous process. Clinically, the appearance ranges from papulosquamous to purpuric. Histopathologically, these reactions simulate a wide variety of lymphoma subtypes; the most frequently reported examples resemble mycosis fungoides. We report a 61‐year‐old female who developed a purpuric eruption prior to engraftment of an autologous hematopoietic stem cell transplant for stage IV mantle cell lymphoma. Skin biopsies showed a superficial perivascular and interstitial infiltrate of large, immature‐appearing mononuclear cells associated with spongiosis, papillary dermal edema and erythrocyte extravasation. The cells were immunoreactive for T‐cell markers and lacked B‐cell marker expression, excluding recurrence of the underlying mantle cell lymphoma as a diagnostic possibility. The cutaneous eruption was temporally linked to levofloxacin administration and resolved after discontinuation of this medication. This is the first report of a lymphomatoid hypersensitivity reaction associated with fluoroquinolone use. The histopathologic features presented in this paper underscore the potential for misdiagnosis of such lesions as lymphoma or acute myeloid leukemia, particularly in the setting of hematopoietic stem cell transplantation for underlying lymphoma or leukemia. Clinical correlation, morphologic comparison to the original malignancy and immunohistochemical studies aid the dermatopathologist in rendering the correct diagnosis.