Evaluation of circulating malignant cells provides prognostic information in cutaneous T cell lymphoma

Peripheral blood lymphocyte morphology was evaluated prospectively by light microscopy of blood smears and E rosette preparations in 160 patients with cutaneous T cell lymphoma (CTCL). Blood involvement was related to the type of cutaneous T-stage, being present in 90% of patients with erythroderma (T4), 27% of those with cutaneous tumors (T3), 9% of those with generalized (T2), and 0% of those with limited skin plaques (T1). Untreated patients with blood involvement (38 of 105) had a higher frequency of CTCL in lymph nodes and viscera and survival inferior to that of patients with normal or nondiagnostic lymphocyte morphology (P < .001). Multivariate analysis showed skin stage and age to be the most important pretreatment risk factors for survival. Although blood involvement was not an independent risk factor for the entire group, it appeared to have some adverse influence in the T2/T3 subsets (P = .051). Both lymphocytosis and size distribution of the circulating CTCL cells at initial diagnosis influenced survival. Patients with 'mixed cell' cytology (>20% large [>11 μm] CTCL cells), had a worse survival than those with predominantly small circulating CTCL cells (P = .009). The former were more likely to have aggressive features, including lymph node effacement by tumor (P < .001) and visceral disease (P = .074), than were 'small cell' patients. Our data indicate that detailed review of the blood lymphocyte morphology in patients with diagnosed or suspected CTCL is helpful in predicting extent of disease and prognosis.