Shared clonality in distinctive lesions of lymphomatoid papulosis and mycosis fungoides occurring in the same patients suggests a common origin.

Lymphomatoid papulosis (LyP) lies within the spectrum of primary cutaneous CD30-positive lymphoproliferative disorders. Approximately 10% to 15% of patients with LyP develop other lymphomas, most commonly mycosis fungoides (MF), suggesting a biological relationship between these distinctive diseases. Here, we describe the clinical and histopathologic features of 11 patients who had both LyP and MF, including a total of 30 biopsy specimens (14 LyP and 16 MF). Clinically, LyP lesions were characterized by clustered papules undergoing spontaneous regression and were classified as type A (n = 11), type C (n = 2), or type D (n = 1). All cases of MF were characterized clinically by patch/plaque disease, were stage I or II at the time of diagnosis, and consisted of a CD4-predominant epidermotropic T-cell infiltrate. We used polymerase chain reaction-based methods to assess the TCR-β chain (TCRB) and TCR-γ chain (TCRG) in both LyP and MF lesions of all patients. Monoclonal TCR gene rearrangements were detected in 13 LyP lesions from 10 of 11 patients and in 14 MF lesions from 10 of 11 patients. All 10 patients in whom their skin lesions carried monoclonal TCR gene rearrangements exhibited overlapping clones in both their LyP and MF lesions; additional non-overlapping clones were identified in 3 LyP lesions from 2 patients and 1 MF lesion from another patient. The demonstration of shared monoclonal T-cell receptor gene rearrangements in LyP and MF lesions in almost all patients suggests a common origin between these distinctive clinicopathological diseases.