Extranodal lymphomas are most frequently found in the gastrointestinal tract, and primary pulmonary lymphoma is extremely rare. Primary pulmonary lymphomas represent 3-4% of extranodal lymphomas and <1% of all non- Hodgkins lymphomas [1
]. Most primary lymphomas of the lung arise from the MALT of the bronchus. They are now classified under marginal zone lymphomas according to the REAL classification [2
]. Most patients are asymptomatic at presentation and diagnosed incidentally by radiological pulmonary abnormalities. Cough, dyspnea and hemoptysis can rarely be seen. The lesions are usually multiple and bilateral on CT scans. Bronchoscopy is usually normal, particularly when the lesions are small. Surgical resection is the preferred treatment modality for localised tumors. Chemotherapy is reserved for patients with bilateral or extrapulmonary involvement, relapse or progression. Radiotherapy is rarely used [1
]. The differential diagnosis of solitary pulmonary nodules is extensive. Most solitary nodules are granulomas, hamartomas or lung cancer. Positron emission tomography (PET) is becoming a frontline imaging choice for the evaluation of solitary pulmonary nodules, with a sensitivity of 94% and specificity of 84% for nodules 1-3 cm in diameter [3
]. However MALT lymphomas usually can not be visualised with PET scan and a negative scan does not exclude MALT lymphoma [5
Of note, autoimmune diseases can be seen in patients with MALT lymphoma. In one study, twenty-nine percent of the patients had an autoimmune disease preceding lymphoma . Autoimmunity markers of our patient were negative except ANA, which might be a harbinger of future SLE or a non-specific finding.
In conclusion, MALT lymphoma should be kept in mind as a rare but potentially curable entity in the differential diagnosis of patients with a solitary pulmonary nodule.