Follicular Lymphoma Mimicking ‘Adenocarcinoma with Clear Cells and Signet Ring Morphology’

Abstract

Case Presentation 91-year-old female who presented with epigastric pain. CT showed a 13 cm mass in the right lower quadrant encasing the right colon and enlarged lymph nodes. Histology of the CT guided biopsy of the mass showed malignant tumour which was composed mainly of cells with clear, vacuolated cytoplasm and eccentric nuclei (signet-ring like). The cells were surrounded by sclerotic stroma and arranged in a nested configuration (Image 1). Morphological features of carcinoma including keratinisation and glandular differentiation were not evident. Melanin pigment in indicate melanoma was not seen. On immunohistochemistry broad spectrum cytokeratin (AE1/3 and CAM5.2) and SOX10 were negative which would exclude carcinoma and melanoma respectively. The tumour was diffusely positive with CD45 and CD20 confirming B-cell lineage (Image 2). There was positivity with BCL2 and germinal centre makers BCL6 and CD10. Staining with antibodies to CD21 and CD23 confirms the presence of at least partial follicular architecture.