Pulse Granulomas in Interval Appendectomy Specimens: Histochemical Identification of Cellulose Matter

Pulse granuloma is a rare pathologic condition considered to be a benign inflammatory reaction to foreign materials originated from ingested legume matter. As for pulse granulomas of the gastrointestinal tract, association with diverticular diseases is relatively common, but only a few pulse granuloma cases associated with appendicitis have been reported. This report presents histopathologic findings of pulse granuloma lesions observed in two appendectomy cases, with some histochemical examinations of cellulose matter which is reportedly a major component to provoke pulse granuloma reaction. Our patients in both cases were girls in their teens, and they underwent interval appendectomy for acute appendicitis. Both appendectomy specimens revealed ruptured walls with inflammatory granulation tissue with marked foreign body reaction including characteristic collections of ring-like, curled ribbon-like, and/or lobulated nephrosclerosis-like hyaline structures and various foreign bodies, in which microorganisms or amyloid deposition were not identified. The presence of cellulose matter was suggested by Sirius red stain, the IKI (iodine potassium iodide)-H₂SO₄ method, and birefringence by polarized light. Appendectomy materials due to acute appendicitis would include pulse granuloma reaction provoked by ingested materials with cellulose. Pathologists should be familiar with the concept and histopathologic features of pulse granulomas to avoid misinterpreting them as vascular lesions and/or amyloid deposition, or any infectious organisms.