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It was first described by Liebow in 1972 as an angiocentric and angiodestructive lymphoreticular proliferation. Subsequent reports suggested that some cases went on to develop T-cell lymphomas. Later it was suggested that various angiocentric lesions such as lymphomatoid granulomatosis, polymorphic reticulosis, and benign lymphocytic angiitis and granulomatosis be classified under the heading of angiocentric immunoproliferative lesions, and graded (1-3) based on the degree of lymphocytic atypia, the presence of necrosis and polymorphic/monomorphic nature of the infiltrate. Grade 3 lesions were considered synonymous with angiocentric lymphomas. Current view is that lymphomatoid granulomatosis and polymorphic reticulosis should no longer be included together under a group heading of angiocentric immunoproliferative lesions, and classification should be based on the phenotype of the proliferating cell. The proliferating cells in LYG were thought to be T-cells up until it was reported that the atypical lymphoid cells were of B-cell phenotype. Other authors confirmed a predominantly B-cell phenotype, although a T-cell phenotype has occasionally been seen. Other cell types may present with an angiocentric pattern in the lung. The lung is probably a common site most likely due to its large vascular bed. Etiology: - Lymphomatoid granulomatosis is closely associated with EBV. - Patients may have underlying defects in their cell-mediated immunity. (may be congenital , e.g. in association with Wiskott-Aldrich syndrome, or acquired, as in AIDS or treatment for other neoplasms). - May be related to immunosuppression. Both LYG and post-transplant lymphoproliferative disorders, show angiocentricity when involving the lung and contain EBV genome. Clinical presentation: Average age at presentation is about 50 years, predominantly in male. Patients present with vague respiratory symptoms (cough, dyspnoea, haemoptysis and chest pain) and are found to have pulmonary nodules and masses which may cavitate. Imaging generally shows multiple bilateral nodules, but unilateral disease is also described. Site: Although it most commonly affects the lung, it can affect multiple extrapulmonary sites (i.e., skin, nervous system, gastrointestinal tract, liver, spleen, kidney, bladder, muscle, and heart). Prognosis: The prognosis is poor, the median survival being only fourteen months after diagnosis. Microscopic features:
The characteristic histological feature is an angiocentric and angiodestructive infiltrate of a polymorhpous infiltrate, including lymphocytes, immunoblasts, plasma cells, sometimes eosinophils, histiocytes and atypical lymphoid cells. Typically the vessels are permeated rather than undergoing frank necrosis. Other features: - There is a variable population of atypical lymphoid cells. Grading depends on the degree of atypia of these cells. - Necrosis & rarely granuloma formation. Immunohistochemistry : A rich T-cell infiltrate with scattered atypical cells of B-cell phenotype. (Rarely cases with atypical T-cell or CD56-positive cells may be seen). It is important to use immunohistochemistry and molecular analysis to look for evidence of clonality and the presence of Epstein Barr Virus. Differential diagnosis: - Other disorders with an angiocentric/vasculitic component like Wegener’s granulomatosis (no atypical lymphoid population is present within the inflammatory cell infiltrate of Wegener’s granulomatosis and gene rearrangement studies is useful in case of doubt). - Primary pulmonary high grade MALT non-Hodgkin’s lymphoma (diagnosis depends on the presence or absence of angiocentricity and it is noted that primary pulmonary lymphomas in the absence of immunosuppression do not show evidence of EBV infection.
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January
2007
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