Totally ulcerated mucosal fragments by related Diffuse infiltrate consists mainly of small to intermediate-sized mononuclear cells displaying mildly irregular nuclear outlines, condensed chromatin and scant to moderate cytoplasm. Plasmacytoid and plasma-cell-like cells are variably present, ranging from scattered to focally conspicuous, characterized by eccentric nuclei and eosinophilic cytoplasm. Overall cytologic atypia is mild, mitotic figures are infrequent.
The infiltrating cells show diffuse strong positivity for LCA (CD45), confirming hematolymphoid origin. CD20 highlights a focal subset of the small lymphoid cells, while CD3 is negative. CD5 is expressed aberrantly within the lymphoid population in the absence of CD3 expression. BCL2 is focally positive. Cyclin D1and CD56 are negative. The plasmacytoid component demonstrates positivity for CD138 and EMA. Markers of melanocytic differentiation (HMB45, SOX10), epithelial lineage (AE1/AE3 cytokeratin) and neuroendocrine differentiation (synaptophysin, chromogranin) are all negative. Ki-67 is about 12%.
Referred block for immunostaining of endoscopic biopsy from sigmoid mass.
One referred block.
Sigmoid mass, endoscopic biopsy, immunostaining:
COMMENT: