2.2.9 Lymphadenosis Cutis Benigna

Clear epidemiological data on Borrelia lymphocytoma are lacking. Around 1-2% of cases are reported. In a German survey from 2003, 189 out of 3935 borrelia infected patients (4.8%) developed lymphadenosis cutis benigna.

Reactive pseudolymphomatous infiltrate with hyperplasia of lymphatic cells in the early phase after borrelia infection, but sometimes after viral or parasitic infections.

Lymphadenosis cutis benigna is a process that can simulate a cutaneous B-cell-lymphoma, but it behaves in a harmless manner. It is a reactive process. In this type of pseudolymphoma, B – lymphocytes and other inflammatory cells accumulate in the dermis and subcutis as a reaction to stimuli of borrelia antigens.

This specific subset of B- cell type pseudolymphoma, borrelial lymphocytoma, primarily occurs in Europe in areas endemic for the tick Ixodes ricinus. Borrelial lymphocytoma is a tick bite response to infection by Borrelia burgdorferi subsp afzelius and garinii. Causative agents: Borrelia garinii and Borrelia afzelii (both in Europa), not Borrelia burgdorferi sensu strictu.

There are rare reports linking this type of pseudolymphomas to post-viral infections, in particular herpes zoster (post-zoster scar lymphocytoma cutis). Another established subtype is due to persisting reactions to the scabies mite without active but probably mite remnant involvement (persistent nodular arthropod-bite reactions).

In Borrelia lymphocytoma lesions are often indolent soft blue-red nodules up to 5 cm. Post scabies lymphocytomas are localized or often disseminated.

Sites of predilection: In borrelia lymphocytoma the sites of predilection are: loose skin (ear, nipple, scrotum); red-blue lupoid infiltrate (diascopy).

Borrelia IgG and IgM titers raised in Borrelia lymphocytoma. No specific antigen subtype in serology to be detected. Dermatopathology specimen with immunohistochemistry necessary.

Most important is to differentiate the subtypes of pseudolymphomas (see chapter 3.3.14 Pseudolymphomas) and to exclude malignant B-or T-cell infiltrates from skin or systemic lymphomas. Epidermis not involved. Dermis with V-pattern top down mature relatively sharp demarcated nodular infiltrates of lymphocytes, plasma cells, follicle center cells, macrophages and sometimes eosinophils. Characteristic is an infiltrate-free zone beneath the epidermis. Expression of B-cell-epitopes (CD20, CD79a). No monoclonal rearrangement of immunoglobulins of heavy or light chains. Sometimes it will show a picture of mature lymph node tissue.

Depends on subtype. In borrelia lymphocytoma after adequate 2nd stage oral doxycycline over 3 weeks, slow fading of lesion(s). In post-scabies pseudolymphoma after adaequate internal antiparasitic drugs and additional change of topical agent, complete but slow healing. Post herpes scar lymphocytoma up to 1-2 months healing.

Depending on subtype. Antibiotics (doxycycline 100 mg b.i.d. for 3 weeks) in borrelia lymphocytoma. Ivermectin orally for post scabies manifestation. Post herpes zoster scar pseudolymphoma topical corticosteroids are recommended.