Abstract

Mycosis fungoides bullosa is a rare clinical subtype of mycosis fungoides, with less than 40 cases reported in the literature. We report a case of a 66-year-old female with a history of stage IIB folliculotrophic mycosis fungoides with large cell transformation, currently being treated with romidepsin and gemcitabine, transferred to our institution due to worsening cutaneous involvement. On exam, there were large, erythematous, crusted and eroded plaques of the neck, trunk, and bilateral upper and lower extremities, some with overlying tense bullae. Punch biopsy showed a marked infiltrate of atypical CD3+ lymphocytes with epidermotropism of predominantly CD4+ cells (CD4:CD8 ratio of 8:1), loss of CD5 and CD7, and scattered CD30+ cells. Direct immunofluorescence showed a non-diagnostic staining pattern. Blood cultures were negative. Given the clinical and histopathologic findings, a diagnosis of mycosis fungoides bullosa was made. Mycosis fungoides is the most common type of cutaneous T-cell lymphoma. Mycosis fungoides bullosa, a vesiculobullous presentation of mycosis fungoides, is a rare variant first described by Dr. Moritz Kaposi in 1887. Proposed mechanisms of bullae formation include confluence of Pautrier’s microabscesses or loss of keratinocyte cohesion due to proliferation of atypical lymphocytes. Diagnosis is based on the presence of vesiculobullous lesions among typical lesions of mycosis fungoides, histopathologic features consistent with mycosis fungoides, and negative evaluation for other causes of vesiculobullous lesions such as infection and autoimmune blistering diseases. Recognition is important as mycosis fungoides bullosa carries poor prognosis, with 50% of reported patients expiring within 1 year of bullae appearance.