Primary pulmonary lymphoma is rare. The most common histological type is the bronchus-associated lymphoid tissue lymphoma. This type of lymphoma has an indolent course and excellent response to therapy. One-third of all cases are diagnosed incidentally. However, due to the rarity of this disease, little is known about its natural history in terms of dissemination and evolution. Herein, we report the unusual case of a 61-year-old man who refused treatment after being diagnosed with bronchus-associated lymphoid tissue lymphoma and died 2 years later from massive lung infiltration without dissemination to other organs.

Keywords: Lung; Autopsy; Lymphoma.

Tumors of the anterior mediastinum include several entities with different radiological and clinical manifestations, constituting a heterogeneous group of congenital, inflammatory, and neoplastic conditions. Among these lesions, the most common primary tumor of the mediastinum is thymoma, nearly followed by germ cell tumors and lymphomas. Tuberculosis of the thymus, an extremely rare condition, typically involves the mediastinal lymph nodes. We present, in this study, pathological, radiological, and clinical findings of one case of tuberculosis of the thymus in an 18-year-old patient who presented thoracic pain, dyspnea upon minimal effort, and progressive worsening of the symptoms in one week. The chest X-ray showed a large mass in the mediastinum, and computed tomography scans indicated that it was located anteriorly. The patient was submitted to surgery in order to excise the mass. Microscopy revealed a massive inflammatory response and granulomas in the thymic tissue. Ziehl-Neelsen staining for acid-fast bacilli yielded positive results, and a diagnosis of tuberculosis was made. Surgeons and pathologists should remain alert for this condition and should include it in the differential diagnosis of mediastinal masses.

Keywords: Thymus; Tuberculosis; Thoracic surgery; Pathology.

Macrophage activation syndrome is a rare and potentially life-threatening disease. It occurs due to immune dysregulation manifested as excessive macrophage proliferation, typically causing hepatosplenomegaly, pancytopenia and hepatic dysfunction. Here, we report an unusual case of macrophage activation syndrome presenting as dyspnea, as well as (reported here for the first time) high resolution computed tomography findings of an excavated nodule, diffuse ground glass opacities and consolidations (mimicking severe pneumonia or alveolar hemorrhage). The patient was successfully treated with human immunoglobulin. We recommend that macrophage activation syndrome be considered in the differential diagnosis of respiratory failure. Rapid diagnosis and treatment are essential to achieving favorable outcomes in patients with this syndrome.

Keywords: Macrophage activation; Lymphohistiocytosis, hemophagocytic; Tomography, X-ray computed; Lung diseases, interstitial.

Objective: To review the pathological diagnosis of possible cases and/or hidden cases of malignant mesothelioma (MM) between 2000 and 2012 using the Hospital-Based Cancer Registry database in the state of São Paulo, Brazil. Methods: Possible cases were retrieved by assessing the database. Inclusion criteria were being older than 30 years of age and having ICD-O-3 topography and morphology codes related to MM. A board of expert pathologists reviewed the pathology reports and requested paraffin blocks in cases that demanded revision. After staining with calretinin, D2-40, WT-1 (as positive MM markers) and Ber-EP4 and MOC31 (as negative MM markers), cases were divided and studied independently by a pair of pathologists to confirm or discard the diagnosis of MM. Results: Our sample comprised 482 cases from 25 hospitals, and 130 needed further histological revision. We received 73 paraffin blocks with adequate material. After board analysis, there were 9 cases with a definitive diagnosis of MM, improving the diagnostic rate in 12%. Two cases of previously diagnosed MM were discarded by review. Conclusions: Our results confirm that part of MM underdiagnosis and underreporting in Brazil is due to incomplete or mistaken pathological diagnosis.

Keywords: Mesothelioma, malignant/pathology; Mesothelioma, malignant/diagnosis; Immunohistochemistry; Registries.