Background: Unusual papulovesicular lesions resembling arthropod bites have been described in patients with chronic lymphocytic leukemia (CLL). Objective: Our purpose was to describe and characterize further the clinical, histopathologic, and immunopathologic features of these lesions. Methods: Eight patients were identified retrospectively who had CLL and characteristic skin lesions. Clinical and histologic features were recorded. Skin biopsy specimens were analyzed immunohistochemically for eosinophil granule major basic protein, eosinophil-derived neurotoxin, neutrophil elastase, and mast cell tryptase. Results: The clinical features, including the lesional distribution, suggested arthropod bites, although most patients could not recall having been bitten. Mixed T- and B-cell lymphoid cell infiltrates were present within lesions, along with prominent eosinophil infiltration and eosinophil granule protein deposition. Conclusion: Exuberant papulovesicular lesions develop in patients with CLL apparently as an exaggerated response to arthropod bites. Prominent eosinophil infiltration and degranulation within these lesions likely contribute to the severity of symptoms. (J Am Acad Dermatol 1998;39:27-35.)