T-cell papulosis associated with B-cell malignancy: a distinctive clinicopathologic entity

Abstract

Background

A distinctive eruption referred to as "insect bite-like reaction", or "eosinophilic dermatosis of hematologic malignancy" has been described during the course of hematological B-cell malignancies (BCM). However, its clinical evolution, histopathological features and pathogenesis remain unclear.

Objectives

To characterize this eruption and to investigate its pathogenesis and relationship with the underlying BCM.

Methods

In this multicenter retrospective study of the French Study Group on Cutaneous Lymphomas, 37 patients with a BCM and a cutaneous eruption consisting in chronic and/or recurrent papules, papulo-vesicles and/or nodules were included. Clinical, histopathological, immunohistochemical and molecular data were reviewed.

Results

No significant insect bite history or seasonal predominance was recorded. Patients had pruritic papules (81%), papulo-vesicles (43%) and nodules (38%), often predominated in the head and neck region (84%), without complete remission periods in most cases (57%). The predominant associated BCM was chronic lymphocytic leukemia (73%). Histological and immunohistochemical review showed: a dense dermal lymphocytic infiltrate predominantly composed of T lymphocytes (100%), with frequent eosinophils (77.6%); a perivascular and periadnexial (most often pilotropic) pattern (77.6%), sometimes suggestive of a pilotropic mycosis fungoides; clusters of tumor B-cells were identified in 47% of cases using appropriate phenotyping markers. In 10/14 cases (71.4%) tested for B-cell IgH gene rearrangement, a B-cell clone was identified in skin lesions (identical to the blood clone in 9 cases), whereas no T-cell clone was present.

Conclusion

We propose the denomination "T-cell papulosis associated with B-cell malignancy" (TCP-BCM) for this distinctive eruption. Although resulting in various histopathological pictures, it can be easily recognized by clinicians, and may be identified by informed pathologists relying on some key features. An extravasation of tumor B-cells with skin-homing properties associated with a secondary, predominant, T-cell immune reaction could explain the clinico-pathologic aspect and the prolonged regressive and recurrent course of the disease.

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