Microscopic description and IHC:

The key finding in this biopsy is the absence of plasma cells.

The biopsy shows mild crypt architectural change. The lamina propria is expanded by many histiocytes (highlighted by CD68 stain). AFB and GMS stains were negative for microorganisms (not shown).

Discussion:

This patient has a history of common variable immunodeficiency (CVID), which is characterized by a host of gastrointestinal (GI) lesions that can mimic many conditions. In the colon, it can mimic Crohn’s colitis with crypt distortion, cryptitis, and granulomas. The diagnosis of CVID may be suspected on the basis of the lack of plasma cells in a GI biopsy. Unfortunately, up to 2/3rd of the patients may not have this feature, making the diagnosis difficult without supporting clinical and laboratory data.

In this case the colonic mucosa is infiltrated by numerous histiocytes as a benign reactive process.

Table of (CVID)
References:

Daniels, Jason A., et al. "Gastrointestinal tract pathology in patients with common variable immunodeficiency (CVID): a clinicopathologic study and review." The American journal of surgical pathology 31.12 (2007): 1800-1812.

CASE IMAGES