Lymphomatoid papulosis: a practical review for pathologists.

Area of Science:

• Dermatology
• Hematology
• Pathology

Background:

• Lymphomatoid papulosis (LyP) is a primary cutaneous CD30+ lymphoproliferative disorder.
• Characterized by chronic, recurrent, self-healing skin lesions (papules/nodules).
• Exhibits an indolent clinical course with spontaneous regression or waxing/waning evolution.

Purpose of the Study:

• To review updated clinical, histopathological, and molecular features of LyP.
• To provide practical diagnostic assessment for differential diagnoses.
• To summarize current understanding of LyP subtypes and their implications.

Main Methods:

• Literature review of clinical, histopathological, and molecular data on LyP.
• Analysis of diagnostic criteria, including CD30 positivity.
• Examination of LyP subclassification (A-E) and associated molecular findings (DUSP22/IRF4).

Main Results:

• LyP diagnosis is based on CD30 positivity, with a broad histopathologic spectrum.
• Subclassification (A-E) is associated with DUSP22/IRF4 rearrangements but does not impact prognosis.
• Treatment focuses on symptom relief and regression, irrespective of subtype.

Conclusions:

• LyP is a CD30+ lymphoproliferative disorder with variable histology but consistent clinical behavior.
• Subtyping aids in differential diagnosis awareness but not in prognostic or therapeutic decisions.
• Accurate diagnosis and understanding of LyP characteristics are crucial for patient management.