Mistaken clinical and pathologic diagnoses of Hodgkin's disease: a Southwest oncology group study.

Expert hematopathology review of initial diagnostic material was required for patients registered in a Southwest Oncology Group trial of advanced Hodgkin's disease (HD). Of 287 cases reviewed, 36 (13%) had been misdiagnosed as HD. The clinical and histologic features of the first 180 patients reviewed by the expert panel, including 21 (12%) patients for whom errors in diagnosis were discovered, were retrospectively analyzed to ascertain why mistakes in diagnosis had occurred. The most common error in pathologic interpretation was to confuse other malignant lymphomas with HD (14/21 patients), particularly large cell lymphomas with pleomorphic features and Reed-Sternberg-like cells. Rare conditions (Lennert's lymphoma or angioimmunoblastic lymphadenopathy) were also confused with HD. Mixed-cellularity and lymphocyte-depleted HD were the most frequently mistaken cell types (14/21 patients) and nodular-sclerosing HD was the least mistaken (two of 21). The clinical features of these 21 patients showed a high incidence of unusual extranodal sites of disease involvement including thyroid (one patient), ovary (one), skin (two), bone (three), and lung (seven). We next analyzed the clinical features of the remaining 107 cases in order to prospectively identify, based on atypical clinical preparations, patients who might not have HD. Subsequent histologic review revealed mistaken diagnosis in 15 patients (14%). Eight of the 15 patients (53%) were correctly identified as having disease other than HD on the basis of clinical presentation alone. Atypical clinical presentations, particularly unusual extranodal sites of disease along with a presumptive diagnosis of mixed cellularity or lymphocyte-depleted HD, should forewarn the clinical and the pathologist of a possible error in diagnosis.