Neutrophil/eosinophil-rich type of primary cutaneous anaplastic large cell lymphoma: a clinicopathological, immunophenotypic and molecular study of nine cases.

AIMS: To elucidate the clinicopathological, immunophenotypic and molecular features of neutrophil/eosinophil-rich primary cutaneous anaplastic large cell lymphoma (CALCL), and to emphasize the cutaneous manifestations, differential diagnosis and prognosis of this peculiar entity.

METHODS AND RESULTS: We described the clinical presentations, histopathology, immunophenotype, molecular features and follow-up courses of nine neutrophil/eosinophil-rich CALCL cases. Various clinical lesions including multiple nodules, plaques and solitary exophytic masses with or without ulceration or crusting were noted in nine patients. Two patients died of disease progression, with one developing multiple lymph node involvement. Histologically, cohesive sheets or small clusters of neoplastic cells were admixed with large numbers of neutrophils and/or eosinophils, representing 10-40% of cells per high-power field. All nine cases showed T-cell phenotypes. The frequency of rearranged TCRB, TCRG and TCRD genes in six cases with available paraffin-embedded tissue was 100%, 83% and 33%, respectively.

CONCLUSIONS: Neutrophil/eosinophil-rich CALCL should be differentiated from various infectious and non-infectious diseases, especially from non-neoplastic cutaneous CD30+ infiltrates rich in neutrophils and eosinophils. Precise correlation of clinical presentation, morphological features, phenotypic and molecular analysis can help to establish the correct diagnosis. Whether this rare variant has a significantly different prognosis from classical CALCL needs further investigation.