צורה כתמית של לימפומה ראשונית של העור מסוג low-grade B - הרחבת הספקטרום הקליניקופתולוגי המוכר

*The first two authors contributed equally to the work.

Background: Primary cutaneous B-cell lymphoma (PCBCL) usually presents with infiltrated-plaques, nodules or tumors. Previous reports of macular PCBCL are scarce and lack detailed clinicopathological correlation.

Aim: To report our experience with PCBCL presenting with erythematous macules.
Methods: Clinicopathological data were collected retrospectively from patients with low-grade PCBCL manifesting with erythematous patches, diagnosed and managed between 1/2000-12/2019 at the tertiary cutaneous-lymphoma outpatient-clinics of-Rabin- or Sheba Medical Centers.

Results: There were 14 patients, (12 male), aged 16-67 years: 9 with primary cutaneous follicle-center cell lymphoma (PCFCL) and 5 with primary cutaneous-marginal zone lymphoma (PCMZL). All had erythematous macules, measuring
1-15cm, distributed among various sites, and mimicked figurate erythema, interstitial-granuloma annulare, livedo reticularis, vascular tumors (mainly-angiosarcoma), or mycosis fungoides. In 2, macules were the sole manifestation, whereas in 12, typical PCBCL-lesions also appeared during disease course. Biopsy-study of the macular lesions yielded in all superficial and deep perivascular±periadnexal lymphoid-infiltrates, with micronodular formation in 12, and nodular infiltrate in 5/12.
In 2 patients, peri-infundibular infiltrate was observed, leading clinically to follicular accentuation in their patches.
B-cells comprised the majority of the lymphocytes in only 4 patients (3-PCFCL, 1-PCMZL), and even then, they accounted for only 60%. In the remaining 10, B and T-cells were either equally distributed (6 patients), or T-cells outnumbered B.
PCR-IgH-gene-rearrangement, performed from a patch of 10 patients, showed a monoclonal rearrangement in 3/6-PCFCL, and in 3/4-PCMZL-cases.

Conclusions: PCFCL and PCMZL can manifest with erythematous macules, usually but not necessarily in combination with typical low-grade PCBCL-lesions. Physicians and pathologists should be aware of this unique presentation.