A CD4+ CD56+ natural killer-like T-cell systemic lymphoma with haemorrhagic cutaneous manifestations

Leucémie aleucémique non T non B CD4+ CD56+ (2 cas)

INTRODUCTION

Non T non B CD4+ CD56+ leukemia is often revealed by cutaneous lesions. We report 2 patients with this disorder who had characteristic anatomoclinical findings.

CASE REPORTS

An 81 year-old female and a 75 year-old man presented with erythematous macules which increased in number and progressed to infiltrated plaques and nodules. The lesions became ecchymotic, but the patients remained in good general condition and blood count as well as bone marrow examination were unremarkable. A cutaneous biopsy revealed a lymphomatous mononuclear cell infiltrate. The cells expressed CD4 and CD56, but not CD3. The cutaneous lesions preceded for 10 and 9 months respectively the appearance of overt leukemia and medullar involvement. At this stage, the patients deceased rapidly from their leukemia.

DISCUSSION

This is an original anatomoclinical syndrome. The histopathologist must pay attention to the unusual CD4+ and CD3- immunophenotype and search for CD56 expression. The malignant cell responsible for this type of leukemia is now individualized and corresponds to a type II dendritic cell precursor.

Plasmacytoid dendritic cells: from the plasmacytoid T-cell to type 2 dendritic cells CD4+CD56+ malignancies

Recent identification of CD4(+)CD56(+) malignancies as pathological counterparts of the precursors of type 2 dendritic cells (DC2) has shed new light on a leukocyte lineage that long remained elusive. This review retraces how knowledge evolved, through careful examination and analysis of both normal lymphoid tissue and rare proliferative diseases, from plasmacytoid T cells to plasmacytoid dendritic cells (pDC) and then DC2. The functions of these cells and their key role at the crossroads of innate and cognitive immunity are also discussed. The major characteristics of DC2 malignancies are summarized and compared to natural killer cell (NK) lymphomas, another type of proliferative disease sharing the expression of CD56.

Agranular CD4+/CD56+ cutaneous neoplasm

CD4+ CD56+ cutaneous neoplasm with hematological relapse is a rare malignant disease and has been described recently in the literature as blastic or agranular NK-cell leukemia/lymphoma. The origin of this neoplasm is uncertain. We describe a 75-year-old patient with a primary cutaneous neoplasm CD4+ CD56+ who evolved to leukemic phase despite standard lymphoma chemotherapy. Morphologically, the cells were undifferentiated without granules in the cytoplasm. The immunophenotype showed the expression of CD4, CD56, CD68, CD33, CD7, CD2, CD45RA, and CD38. Histological analysis revealed a cell infiltration mainly located in the dermis. T-cell receptor and immunoglobulin heavy chain genes were in germline configuration. Cytogenetic study showed complex structural abnormalities with a deletion of the chromosome 5 del(5q). The clinical course was aggressive with an early hematological relapse.