Accuracy in diagnosis of lymphomatoid papulosis

This study was undertaken to assess the accuracy of histologic diagnosis of lymphomatoid papulosis (LyP), which may be confused with malignant lymphoma or other entities. It is essential that accurate diagnoses be made because LyP may be a marker for malignant lymphoma. All 15 examples of LyP reviewed in a dermatopathology laboratory during a 14-year period and 180 histologic sections of tissue that could be confused with LyP were reviewed. Criteria for diagnosis of LyP were applied without benefit of clinical history, and revised diagnoses were made where indicated. Clinical follow-up information was obtained and original accuracy of diagnosis was assessed by comparing clinical courses with original histologic diagnoses. In cases of LyP in which numerous atypical lymphoid cells were present, 100% accuracy was noted. When fewer atypical lymphoid cells were present and inflammatory cell infiltrates were less dense, the diagnosis was less certain. Overall, a 64% correlation of clinical course and histologic diagnosis of LyP was noted. We conclude that the histologic diagnosis of LyP is generally reliable and accurate; however, in some cases a precise diagnosis cannot be made with certainty. Cases with fewer atypical lymphoid cells may fail to correlate well with the classic course of LyP and may represent a variant or histologic simulator.