Asbestos related interstitial pneumonitis associated with glomerulonephritis and lymphomatoid granulomatosis

Pulmonary lymphomatoid granulomatosis in seven dogs (1976-1987)

Seven dogs with pulmonary lymphomatoid granulomatosis were reviewed. The disease occurred in six large-breed and one small-breed dogs. The dogs were five to 14 years old (mean, 8.4; median, 7), and four of seven dogs were males. Three dogs had been previously treated with adulticide therapy for canine dirofilariasis. Clinical histories included a progressive respiratory disease characterized by varying degrees of cough, dyspnea, exercise intolerance, and weight loss. Thoracic radiographic features included hilar lymphadenopathy, pulmonary masses of varying sizes, and mixed pulmonary patterns of lobar consolidation with ill-defined interstitial and alveolar pulmonary infiltrates. Cardiovascular changes compatible with chronic dirofilariasis were present in three dogs. The clinical course was usually progressive and fatal. The survival time ranged from six days to four years (mean, 12.5 mos; median, 3 mos). Gross and histologic features included mass lesions with areas of necrosis that replaced normal pulmonary architecture. Cytologically, these lesions were characterized by infiltration with pleomorphic, angioinvasive mononuclear cells that often resulted in vascular obliteration. The infiltrating cells resembled large lymphoid cells that possessed large hyperchromatic nuclei and small amounts of cytoplasm. Systemic lymphoid neoplasia with peripheral lymphadenopathy was diagnosed in two dogs. In both cases, lymph-node cytology was similar to the cellular infiltrates found in the lungs and consistent with a diagnosis of lymphomatoid granulomatosis. These features are compared with previously reported cases of canine lymphomatoid granulomatosis and those features identified in a similar disease described in man.

Lymphohistiocytoid mesothelioma: a rare lymphomatoid variant of predominantly sarcomatoid mesothelioma

Of 394 "definite" mesotheliomas entered in the Australian Mesothelioma Surveillance Program, three bore a striking resemblance to malignant lymphoma by conventional light microscopy, and each was misinterpreted at some stage as lymphoma. The lymphoma-like morphology was a combined result of intense lymphoplasmacytic infiltration and the histiocytoid appearances of the underlying neoplastic cell population. Immunocytochemical analysis demonstrated cytokeratins coexpressed with vimentin within the tumor cells, whereas immunoreactivity for leukocyte common antigen was confined to the smaller lymphoid cells. Electron microscopy of two cases revealed a polymorphous population of fibrohistiocytic cells resembling those typical of malignant fibrous histiocytoma, admixed with lymphocytes and plasma cells, but sporadic cells expressed mesothelial properties in the form of sinuous villiform processes, intracytoplasmic neolumina lined by microvilli, and intermediate filaments that were aggregated into tonofilament bundles in some cells. The ultrastructural appearances, the localization of the tumors to the pleura, with effusion, and absence of anterior mediastinal mass lesions facilitated exclusion of lymphocyte-rich thymoma. In addition, a history of prior occupational exposure to asbestos was elicited in each instance. There was no apparent response to radiotherapy or chemotherapy, and the patients died at 4, 5, and 8 months after presentation. Our observations suggest that immunocytochemical or ultrastructural evaluation is mandatory for accurate diagnosis of all pleura-based lymphomatoid lesions with a mixed large and small cell pattern.