Yersinia appendicitis

Synopsis

 transmural epithelioid cell granulomas (EPGs)

• predominantly nonsuppurative
• surrounded by a lymphoid cuff composed of small lymphocytes.

 suppurative granulomas

• EPGs with suppuration of the centers of the granulomas (central microabscesses)

 EPGs composed of numerous histiocytes with or without epithelioid cell features, along with scattered small T-lymphocytes and plasmacytoid monocytes.

• None of the EPGs contain monocytoid B-cells.

Immunohistochemical study

 EPGs usually surrounded by surface IgM/D+ small mantle zone lymphocytes.
 CNA.42 immunostaining occasionally demonstrated residual follicular dendritic cells in the center of the EPGs.

Types

 Yersinia enterocolitica appendicitis (17189675)

Differential diagnosis

 cat scratch disease (numerous monocytoid B-cells)
 lymphogranuloma venerum (numerous monocytoid B-cells)

References

 Kojima M, Morita Y, Shimizu K, Yoshida T, Yamada I, Togo T, Johshita T. Immunohistological findings of suppurative granulomas of Yersinia enterocolitica appendicitis: a report of two cases. Pathol Res Pract. 2007;203(2):115-9. PMID: 17189675