Borrelial lymphocytoma cutis
BL; Borrelia lymphocytoma; lymphocytoma cutis; lymphadenosis benigna cutis; Spiegler-Fendt sarcoid
Borrelial lymphocytoma cutis is a cutaneous pseudolymphoma representing a hyperplastic immune response to Borrelia afzelii infection — a recognised intermediate-stage manifestation of European Lyme borreliosis. It presents typically as a single bluish-red infiltrated nodule or plaque on the earlobe (commonest in children), nipple-areola complex or scrotum (commonest in adults), 1–6 months after an Ixodes tick bite. Histology shows a dense polyclonal B-cell infiltrate with reactive germinal centres — closely mimicking primary cutaneous marginal zone lymphoma. Recognition is clinically important because antibiotic treatment (doxycycline) resolves the lesion within weeks; misdiagnosis as PCMZL leads to unnecessary RT or rituximab. Pairs with the existing PCMZL Borrelia-association content.
Clinical features
- Solitary firm bluish-red to violaceous nodule or plaque, 1–5 cm.
- Predilection sites — earlobe (commonest, particularly in children), nipple-areola complex (in adults), scrotum, axilla.
- Develops 1–6 months after Ixodes tick exposure / EM.
- Slow growth; usually asymptomatic.
- Often unilateral; reflects local lymphocytic response to Borrelia.
- European Lyme (B. afzelii dominant); rare or absent in North America.
Diagnosis
- Borrelia serology — IgG ELISA + Western blot; usually positive (in contrast to early EM where serology often negative).
- Skin biopsy:
- Dense polyclonal B-cell infiltrate with reactive germinal centres in the dermis.
- Mixed cell population — small B cells, plasma cells, scattered T cells, sometimes eosinophils.
- BCL2 negative or weakly positive (reactive); BCL6+, CD20+, CD79a+.
- Light-chain polyclonality (kappa : lambda ratio ~ 2:1 — within reactive range).
- Tissue PCR for Borrelia — variable yield but supportive when positive.
- Critical differential is primary cutaneous marginal zone lymphoma — same site, similar histology, but PCMZL shows light-chain restriction, IgH gene rearrangement on PCR.
Management
- Doxycycline 100 mg twice daily for 21–30 days — first-line.
- Alternative — amoxicillin 1 g three times daily for 21 days; ceftriaxone 2 g IV daily for 14 days (severe disease).
- Resolution typically within weeks; complete regression confirms the diagnosis.
- If no response to antibiotics, reconsider PCMZL or other cutaneous B-cell lymphoma — see PCMZL.
- Excision is rarely needed once Borrelia is confirmed.
References
- Stanek G et al. Lyme borreliosis. Lancet; 2012.
- Colli C et al. Borrelia burgdorferi-associated lymphocytoma cutis — clinicopathologic, immunophenotypic and molecular study of 106 cases. J Cutan Pathol; 2004.
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