Pathology
Macroscopy: A. Four pieces of tissue up to 3 mm. B. Four pieces of tissue up to 3 mm.
Microscopy: A. The specimen comprises superficial bronchial mucosa with foci of atypical cellular infiltrate comprising predominantly large atypical cells with irregular nuclear membranes, vesicular chromatin, macronucleoli and minimal amounts of delicate cytoplasm. In some areas, the large atypical cells form sheets and in other areas, they are admixed with small lymphocytes and histiocytes.
Immunohistochemical stains: The large atypical cells are diffusely positive for CD20, CD79a and PAX-5 which show co-expression of MUM-1 and BCL-6 but not CD10. C-myc positivity is seen in approximately 50% of cells and BCL-2 positivity is seen in approximately 10% of cells. The proliferation index as estimated by a stain for ki67 is 70%. The tumour cells are negative for CD30 and EBV-LMP.
Foci of admixed small numbers of CD3 positive T cells and CD68 positive histiocytes are demonstrated.
B. The sections show fragments of bronchial mucosa with a focal atypical cellular infiltrate with morphological features as described for specimen A.
Endobronchial biopsies: Large B cell lymphoma. Final classification requires further stains and clinical correlation. See the discussion below:
The findings are of a large B cell lymphoma. The differential diagnosis includes diffuse large B cell lymphoma, NOS, non-germinal centre type and, given the clinical history of multiple cavitating pulmonary nodules, Lymphomatoid granulomatosis (grade 3). EBER-ISH is being performed to evaluate this possibility. Please correlate with other clinical findings.