Low-grade lymphoma

Clinical History

A 56-year-old woman, asymptomatic, non-smoker and without relevant medical history, underwent a preoperative chest X-ray for safenectomy in April 2005 (Fig. 1) showing multiple opacities in both lungs.

Imaging Findings

CT of the chest confirmed the presence of parenchymal abnormalities (Fig. 2). Bronchoscopy with bronchoalveolar lavage did not demonstrate atypical cells suggestive of malignancy. In January 2006 the patient was referred to our hospital because of persistence of chest opacities. She did not report any symptoms. Pulmonary functional tests, blood gas analysis, DLCO, walking test, laboratory and immunological tests as well as neoplastic markers were negative. Chest CT (Fig. 3) and bronchoscopy with multiple transbronchial biopsies were then performed.
Fig.1: Chest radiograph (frontal view) shows multiple and bilateral homogeneous opacities, predominantly with ill-defined margins, in both mid and lower zones of the lungs.
Fig.2-3: Chest CT scans (axial images) demonstrate multiple and bilateral airspace consolidations with subpleural and peribronchovascular distribution, associated with multiple small nodules along the bronchovascular bundles, mainly located in the lower lobes. No hilar and mediastinal lymphadenopathy is detected.
Fig.4-5: A nine-months follow-up chest CT shows a substantial stability of the pulmonary abnormalities.
Potential diagnoses were Bronchioloalveolar carcinoma, Organizing pneumonia, Sarcoidosis, Low-grade lymphoma (MALT or BALT lymphoma) or Wegener´s granulomatosis.
Histological Findings:
Fig.6: Transbronchial biopsy specimen stained with hematoxilin-eosin shows monotonous infiltrate of small lymphocytes with clear cytoplasm (monocytoid cells) invading bronchial and bronchiolar epithelium (lymphoepithelial lesions).
Fig.7: Immunohistochemical staining (brown color) for CD20, a B-cell marker, shows positive neoplastic lymphocytes blended with normal nonstained cells of bronchiolar epithelium.
Fig.8: The analysis of immunoglobulin heavy gene rearrangement by PCR of the sample (A) shows a monoclonal bundle, like bundle D, suggestive of monoclonal neoplastic proliferation.

Discussion

Histological and immunoistochemical findings of our case were coherent with B-cell Lymphoma of Bronchus-Associated Lymphoid Tissue (BALT Lymphoma), a rare disorder which represents a subgroup of low-grade B-cell extranodal non-Hodgkin's lymphoma, classified as marginal zone lymphoma. BALT lymphoma is slow-growing neoplasm with apparently benign clinicopathologic features. It complicates the Sjogren’s syndrome in about 25% of patients; it may be also seen in patients with dysgammaglobinemia, collagen vascular diseases and AIDS as well as in patients without known autoimmune disorder or chronic antigenic stimulus.
Patients range in age from 25 to 85 years and are often asymptomatic. The prognosis of BALT lymphoma depends on the predominant cell type and the disease stage. Recommended treatment options include, surgical resection for limited disease, radiotherapy and immunosuppressive chemotherapy for locally advanced and disseminated diseases respectively. Recurrence is seen in 10%–15% of cases.
The commonest radiological manifestations of pulmonary BALT lymphoma are solitary or multifocal areas of central or peripheral parenchymal consolidation with air bronchogram, which do not cavitate and are rarely associated with pleural effusion; it may also shows a ground glass appearance. Less common imaging features include multiple unilateral or bilateral nodules and diffuse infiltrates along the bronchovascular bundles and interlobular septa, simulating a perilymphatic spread disease. Hilar and mediastinal lymphadenopathy is not a prominent radiologic finding in BALT lymphomas. In our case, an association of multiple consolidations with peribronchovascular small nodules was observed.
In some patients, chest abnormalities remain stable for several years before biopsy and definitive histologic diagnosis. Multiple persistent air space consolidations may represent a great number of diseases and we should include in the differential diagnosis, bronchioloalveolar carcinoma, organizing pneumonia, as well as Wegener´s granulomatosis or sarcoidosis. An overlap of radiologic findings among these diseases is expected even if they can show some typical appearances. Organizing pneumonia usually shows unilateral or bilateral patchy consolidation with air bronchogram, a peripheral or peribronchial distribution and a lower lobes involvement; nevertheless, consolidations have a tendency to migrate over time and to resolve after steroid therapy. In Wegener´s granulomatosis the most common findings are multiple nodules or irregularly marginated masses with peribronchovascular distribution and no zonal predominance; in approximately 50% of cases, cavitations occur within the nodules and they may resolve with therapy. Sarcoidosis typically demonstrates multiple small nodules with a perilymphatic distribution and upper lobes predominance; consolidation is less commonly seen and coexistence of mediastinal lymphadenopathies can also help in the differentiation. Differential diagnosis with bronchioloalveolar carcinoma is extremely difficult because multiple consolidations with air bronchograms are a common finding and mediastinal lymphadenopaties and pleural effusion are not characteristic as with BALT lymphoma.
In conclusion, CT findings of multiple and bilateral consolidations without cavitations and the absence of mediastinal or hilar nodes may allow to reduce the differential diagnosis. The indolent nature of lesions and a history of autoimmune disease may help perform a proper diagnosis. Tissue confirmation, using core or surgical biopsy with the help of immunohistochemical staining, is generally needed to make the ultimate diagnosis.

Differential Diagnosis List

Final Diagnosis

Low-grade B-cell Lymphoma of Bronchus-Associated Lymphoid Tissue (BALT)

URL:	https://www.eurorad.org/case/7484
DOI:	10.1594/EURORAD/CASE.7484
ISSN:	1563-4086