A retrospective study on diagnostics and treatment outcomes of primary cutaneous B-cell lymphomas

Background: Primary cutaneous B-cell lymphomas (PCBCLs) are a group of commonly indolent diseases that comprises primary cutaneous follicle center lymphoma (PCFCL), primary cutaneous marginal zone lymphoma (PCMZL) and primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL, LT). PCBCLs affect mainly adults but also children. Treatment is watchful waiting, excision, radiotherapy, rituximab, and systemic chemotherapy in case of extracutaneous spread disease. The disease is rare and there is a huge need of studies on clinical features and treatment outcomes. Aim: The aim of the study was to present demographics, clinical features and treatment outcomes of patients with PCBCLs in West Sweden. Methods: This is a descriptive, register-based, single center retrospective study of patients diagnosed with PCBCLs at Department of Dermatology and Venerology at Sahlgrenska University Hospital between 2002-2021. Data regarding demographics, clinical characteristics, pathological- and medical examination findings, comorbidities, staging according to TNM-system and treatment response were collected from patients’ medical records and the hospital-based skin lymphoma register. Results: Nine patients with PCBCLs were identified and included in the study. Mean age at diagnosis was 53.8±14.5 years for patients with PCFCL (n=5) and 49.2±28.1 for PCMZL (n=4), respectively. Skin presentations of PCFCL were in form of papules, plaques and tumors (40%) preferably distributed on the head (60%) and trunk (40%). Papules (75%) on upper extremity (50%) were the most common manifestation in PCMZL. In most cases the histopathological diagnosis was set after the first pathological anatomical diagnosis but for PCFCL it required two or three biopsies before the diagnosis was confirmed. Monoclonality was identified in 20–25% in PCFCL and PCMZL. Lactate dehydrogenase was increased at any time in PCFCL 40% and PCMZL 25%. All the patients with PCFCL were tested for borreliosis and all were negative. One of two PCMZL patients was tested positive for borreliosis. Enlarged lymph node was found in 20% of the patients with PCFCL, all had done a CT. Radiotherapy, excision, topical/intralesional corticosteroids, chemotherapy and rituximab were used to treat PCBCLs. PCMZL had complete remission when treated with chemotherapy, radiotherapy and with excision. The treatments were commonly used as monotherapy or in a combination over time. The study population had a wide range of different comorbidities including cardiovascular diseases, hypothyroidism, rheumatic arthritis and dermatological diseases including malignant melanoma, basal cell carcinoma and herpes zoster. Conclusion: This study contributes to increased knowledge on demographics, clinical features, diagnostics, and treatment response of PCBCLs. The results of the study can be used in future research and adds some new knowledge about these unusual diseases in clinical practice.