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

Area of Science:

• Dermatology
• Hematology
• Oncology

Background:

• A distinct eruption, termed 'insect bite-like reaction' or 'eosinophilic dermatosis of haematological malignancy,' is associated with B-cell malignancies (BCM).
• The clinical course, histopathological findings, and pathogenesis of this eruption were previously unclear.

Purpose of the Study:

• To characterize the clinical and histopathological features of this eruption.
• To investigate its pathogenesis and association with underlying BCM.

Main Methods:

• A multicenter retrospective study involving 37 patients with BCM and a specific cutaneous eruption.
• Review of clinical, histopathological, immunohistochemical, and molecular data.

Main Results:

• The eruption presented as chronic, recurrent, pruritic papules, papulo-vesicles, and nodules, predominantly on the head and neck.
• Histopathology revealed a dense dermal T-cell infiltrate with eosinophils and evidence of B-cell clones in skin lesions.
• Chronic lymphocytic leukemia was the most common associated BCM.

Conclusions:

• The eruption is proposed to be named 'T-cell papulosis associated with B-cell malignancy' (TCP-BCM).
• Key features aid in clinical recognition and pathological identification.
• The pathogenesis may involve B-cell extravasation and a secondary T-cell immune response, explaining the recurrent course.