Cutaneous pseudolymphoma
Definition
- Definition: benign, polyclonal lymphoreticular proliferations, difficult to distinguish from cutaneous lymphomas.
- Important: Pseudolymphomas often regress spontaneously or after trigger elimination — the therapeutic goal is observation of the course + trigger avoidance, not aggressive immunosuppression.
- Histological differentiation from malignant lymphoma: Polyclonality (κ:λ ratio normal), no "top-heavy" infiltrate, good architecture of lymph follicles with reactive centers.
Classification by Etiology
Drug-induced
- Lymphocytic drug reaction — typical triggers: Anticonvulsants + Allopurinol + Ranitidine, clinically maculopapular to plaque-like, histology resembles MF. DD important, as avoidance cures.
Arthropod Reaction / Idiopathic
- Lymphadenosis cutis benigna: Lyme Stage I–II + B-cell infiltrate on earlobes / nipples / scrotum — in children classically on the earlobe. Therapy: Doxycycline 14–21 days; in children before the age of 9 use amoxicillin instead (doxycycline only from the 9th year of life because of tooth discoloration/enamel damage).
Virus-induced Pseudolymphomas
- HSV infection as a trigger for a pseudolymphomatous reaction (Leinweber et al. 2006).
- EBV, Molluscum, HHV infections also described.
Contact Allergy
- Lymphomatoid contact allergy: chronic plaques + T-cell infiltrate to gold salts + cobalt, patch test + avoidance cure.
Unexplained Etiology
- Lymphomatoid Papulosis (LyP): CD30+ T-cell lymphoma with recurrent lesions that heal spontaneously. Subtypes A–F (Histo).
- Actinic Reticuloid (CAD): chronic dermatitis primarily in older men, histology MF-like.
Differential diagnoses
- Dermatofibroma
- Basal cell carcinoma
- Granuloma annulare
- Mycosis fungoides
- Borrelia pseudolymphoma
- Melanoma
- Cutaneous angiosarcoma
- Erythema migrans (Lyme disease)
Practise Cutaneous pseudolymphoma in the app
Flashcards with spaced repetition, exam questions and spot-the-diagnosis on this topic – in DermaFuchs, free of charge.
In the DermaFuchs app: 5 flashcards · 4 clinical images
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Note: This page is intended for medical education and does not replace diagnosis or treatment decisions in individual cases. Treatment and follow-up content is available in the app.