A morbilliform drug eruption is the most common condition leading to a dermatology consultation for a patient in the hospital. Timing is an important diagnostic tool since the onset of a skin rash usually takes place within days-to-weeks of the start of the implicated drug. A comprehensive, thorough, and reliable drug history by the clinician is essential. Therefore, to assist in the task of determining the causative medication of a new skin rash in a hospitalized patient, the creation of a drug calendar is recommended. The development of an electronic version of the drug calendar offers several benefits over the manual version. As the use of electronic medical records continues to become the standard in medicine, the electronic drug calendar will serve as an invaluable tool for the diagnosis of drug hypersensitivity.

Epidermotropic B cell lymphoma represents a rare form of marginal zone lymphoma presenting as a disseminated skin rash resembling pityriasis rosea. To date there are 8 reported cases. In addition to the widespread nature of the skin rash, there is a proclivity for spleen and bone marrow involvement raising consideration regarding its categorization as a systemic lymphoma. We present an 89-year-old man with epidermotropic B cell lymphoma, who presented with a pityriasis rosea-like skin rash. An initial diagnosis of diffuse large cell B cell lymphoma was made based on the extent of dermal-based large cell infiltration. However, after recognizing the epidermotropic component and the distinctive clinical presentation, a diagnosis of epidermotropic B cell lymphoma was rendered. There was minimal bone marrow involvement based only on flow cytometric analysis, but there was no apparent bone marrow or splenic involvement on routine light microscopic assessment. Remission was = achieved with single agent rituximab chemotherapy and the patient remained symptom free. The neoplastic CD20 positive epidermotropic B lymphocytes expressed CXCR3. Similar to the prior reported cases by the authors, the neoplastic cells expressed CXCR3, a chemokine whose organ and tissue specific ligands could contribute to its relatively indolent clinicalcourse.