Diversity of Radiological Imaging and Clinical Course in Pulmonary MALT Lymphoma: A Case Report

Clinical: The patient, who had been admitted to the emergency room with symptoms of dyspnea, hypoxia, and fever, was hospitalized after pleural fluid was exudate and consolidation was detected. Although the patient's clinical symptoms were severe, CRP was moderately high, and the occasional fever despite antibiotic therapy during hospitalization suggested diagnoses such as malignancy and tuberculosis, in addition to non-specific infection.

Lymphomatous proliferation can involve the lung in various ways. Non-Hodgkin or Hodgkin lymphoma can present in the lung through hematogenous spread or by invading from adjacent mediastinal lymph nodes. However, primary involvement of the lung is also possible. Primary lymphomas should not have extra-pulmonary organ involvement for at least 3 months after diagnosis. The most common are MALT and effusion lymphomas (2).

Effusion lymphomas may involve the pericardial and peritoneal cavities, with the most common primary involvement being the pleura, without solid organ involvement. Human-Herpes-8 infection and EBV may be accompanied by fever and lymphocytic-exudative fluid. HHV-8 negative cases have a better prognosis (3).

In this case, there was also an exudative pleural effusion. However, although pleural involvement was not detected in the fluid cytological examination, pleural involvement was detected in biopsies. However, it is not possible to say that the patient only has effusion lymphoma (PEL). MALT (Mucosa-associated Lymphoid Tissue) lymphoma is the type of lymphoma that most commonly involves pulmonary tissue, is often asymptomatic, and shows radiological alveolar opacities. Although it is more commonly affected in people aged 50-60, it can rarely be seen under the age of 30. It constitutes 60% of pulmonary lymphomas. Weight loss and fever are especially prominent during the aggressive phase, though the condition may initially be asymptomatic. Autoimmune disease may be the basis in 16% of cases (1,4). The prognosis of MALT lymphomas is good; 5–10-year survival is more than 80% (5).

Radiological: MALT lymphoma exhibits radiological variability, appearing as single or multiple bilateral lesions on both chest radiography and thoracic tomography. Chronic alveolar localized opacities smaller than 5 cm on radiography are accompanied by consolidation in 50% of cases. Diffuse reticulonodular opacity, atelectasis, and pleural effusion are detected in less than 10% of cases (1). In our case, there was also pleural fluid along with similar findings.

Findings such as consolidation (60-77%) with air bronchogram and increased vascularity or multiple mass nodules, ground glass, halo sign, galaxy sign specific to tuberculosis and sarcoidosis have been reported in case series and reports. In addition, varicose cystic bronchiectasis secondary to consolidation can be detected. However, it is not possible to state that these findings are specific to MALT lymphoma. These radiological images are also observed in adenocarcinoma, pneumonia, metastases, sarcoidosis, and tuberculosis (6,7).

In this case, chest X-ray revealed bilateral multifocal consolidation and densities indicative of pleural effusion. Consolidation, pleural effusion, varicose cystic bronchiectasis changes and mediastinal lymphadenomegaly were detected on thoracic tomography.

None of these radiological findings were specific to lymphoma and diagnosis could not have been made without pathological examination. The partial alleviation of the patient's clinical symptoms compared to the beginning and the patient's relief with the drainage of the pleural fluid suggested possibilities such as infection, alveolar sarcoidosis, or adenocarcinoma when we did not have pathological data. Nevertheless, when intermittent fevers began to occur during the clinical course, it was obvious that lymphoma could not be excluded from the diagnosis. No endobronchial lesion was detected in the bronchoscopy performed on the patient; Wang fine needle aspiration and then endobronchial ultrasonographic biopsy were performed for mediastinal lymphadenomegaly.

The sensitivity and specificity of positron emission tomography (PET-CT) in lymphoma varies according to organ involvement. It has been reported as 80-100% in lung involvement (8, 9). In our case, high SUVmax FDG uptake in consolidated foci in lepidic structure was monitored in PET-CT, and pleural uptake was minimal. The presence of clinical symptoms and high FDG uptake necessitated a video-assisted-thoracoscopic (VATS) procedure.

Pathological: In the pleural fluid sample examined at the start of the treatment, abundant lymphoid cells were detected, but no atypical structures were observed. There were findings of granulomatous inflammation in the samples obtained from the mediastinal lymph nodes of the patient. In fact, in the biopsy samples taken by video-assisted thoracoscopy, low-grade B-cell non-Hodgkin Lymphoma (CD20 positive (diffuse cells), anti-BCL-2 positive, anti Ki-67 low positive) and extra-nodal marginal zone lymphoma were detected in the parietal pleura. Pathologically, the lymphomatous infiltrate in MALT lymphoma exhibits heterogeneous features and consists of small lymphocytes, centrocyte-like cells, monocytoid B cells, rarely large transformed cells and plasma cells (10). Necrosis is rare. Neoplastic cells are expressed in CD 20 and CD 79. Ki67 index is lower than 20%.

Lymphoma and sarcoidosis are similar in terms of clinical and radiological phenotype. Distinguishing low-grade lymphomas from sarcoid lesions can be challenging; sarcoid granulomatous lesions may be accompanied by lymphoid cell infiltration. In addition, sarcoid-like reactions are frequently seen in malignant lymphomas. Moreover, sarcoidosis-lymphoma syndrome was first described in the study by Brincker et al. They reported that lymphoma was 5.5 times more common in sarcoidosis patients than in the general population, indicating the presence of sarcoidosis years before lymphoma (11, 12). Kokuho N et al reported MALT lymphoma in the lung for the first time in a ten-year-old sarcoidosis case with ocular, gastric and lung involvement (13).

In this case, granulomatous inflammation was detected in mediastinal LAMs, but no findings of sarcoidosis were found in ocular, cardiac, renal examinations, angiotensin-converting enzyme, calcium, alkaline phosphatase, and 24-hour urine calcium analyses. There was also no abnormality in abdominal ultrasonography. We believe that the granulomatous inflammation in our case was reactive to immune deficiency.