Diffuse large B-cell lymphoma (DLBCL) is the most common type of malignant lymphoma (ML), accounting for 30%-40% of cases of non-Hodgkin’s lymphoma (NHL) in adults. Primary paranasal sinus lymphoma is a rare presentation of extranodal NHL that accounts for only 0.17% of all lymphomas. ML from the maxillary sinus (MS) is a particularly rare presentation, and is thus often difficult to diagnose. We have reported the first known case of DLBCL originating from the MS with rapidly occurrent multiple skin metastasis.

An 81-year-old Japanese man visited our hospital due to continuous pain for 12 d in the left maxillary nerve area. His medical history included splenectomy due to a traffic injury, an old right cerebral infarction from when he was 74-years-old, hypertension, and type 2 diabetes mellitus. A plain head computed tomography (CT) scan revealed a 3 cm × 3.1 cm × 3 cm sized left MS. On day 25, left diplopia and ptosis occurred, and a follow-up CT on day 31 revealed the growth of the left MS mass. Based on an MS biopsy on day 50, we established a definitive diagnosis of DLBCL, non-germinal center B-cell-like originating from the left MS. The patient was admitted on day 62 due to rapid deterioration of his condition, and a plain CT scan revealed the further growth of the left MS mass, as well as multiple systemic metastasis, including of the skin. A skin biopsy on day 70 was found to be the same as that of the left MS mass. We notified the patient and his family of the disease, and they opted for palliative care, considering on his condition and age. The patient died on day 80.

This case suggests the need for careful, detailed examination, and for careful follow-up, when encountering patients presenting with a mass.

• Diffuse large B cell lymphoma
• Non-germinal center B-cell-like lymphoma
• Malignant lymphoma
• Maxillary sinus
• Skin metastasis
• Case report

Primary pulmonary diffuse large B cell lymphoma (PPDLBCL) is extremely rare, with fewer than 40 cases reported to date and a lack of systemic analysis. Herein, we present a case of PPDLBCL mimicking metastasis in a heavily treated patient with breast cancer. To our knowledge, this is the first reported case of PPDLBCL in a patient with breast cancer. A 66-year-old Chinese female diagnosed with breast cancer 7.5 years previously and multiple bone metastases 31 months later presented with a new-onset subpleural nodule in the inferior lobe of left lung detected by routine follow-up in November 2017. A 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography scan showed that the pulmonary nodule was hypermetabolic with a maximum standard uptake value of 14.9, consistent with lung metastasis in view of her history of breast cancer and multiple bone involvement. Surprisingly, pathologic investigation revealed primary lung DLBCL, staged IEA. Systemic chemotherapy with R-CDOP (rituximab, cyclophosphamide, vindesine, doxorubicin liposome, and prednisone) achieved complete remission with mild side effects. At the latest follow-up in August 2019, the patient had disease-free survival of 21 months. The findings from this case indicate that primary pulmonary lymphoma should be included in the differential diagnostic checklist of pulmonary occupancy, even in solid tumor patients treated with multiple modalities. When a newly developed lung nodule is identified in such patients, clinicians should not take for granted that it is lung metastasis. Pathology results are a prerequisite for making a correct diagnosis, choosing appropriate treatment, and improving patient prognosis.

• case report
• diffuse large B cell
• pathology
• primary pulmonary lymphoma