Given the distinctive appearance of the hyaline rings, the differential diagnostic considerations for pulse granuloma are fairly limited.
Silverman, "Rectal pulse granuloma," Archives of Pathology & Laboratory Medicine, vol.
Guresci, "Pulse granuloma, unusual localization: appendix," The Turkish Journal of Gastroenterology, vol.
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Caption: Figure 2: Pulse granuloma with characteristic dense and eosinophilic hyaline rings within the wall of the gallbladder (H&E, original magnification x400).
Pulse granuloma is a rare benign entity that has also been called oral vegetable granuloma and giant cell hyaline angiopathy. Most of the literature suggests that the pathogenesis is a foreign body reaction to ingested legume parenchymatous cells at various stages of digestion.[1,3-7] Vegetable particles have been demonstrated associated with granulomas and hyaline rings in most of the reported cases in the literature[4,5,8-10] and in 2 reviews of a larger number of cases.[3,6] The histologic and ultrastructural findings of a series of cases of pulse granulomas have also been reported. Animal experiments with injection of vegetable matter in lungs and oral cavity have demonstrated reactions similar to lentil granulomas observed in humans.[3,7]
The literature also contains reports of pulse granulomas occurring in the lungs of patients prone to aspiration, causing lentil aspiration pneumonia.[3,4] To the best of our knowledge, we report the first example of pulse granuloma involving the rectum.
Based on these findings, the diagnosis of pulse granuloma was made.
The majority of pulse granulomas occur in the oral cavity.[1,2,5,6] However, granulomatous reactions to vegetable matter have also been described in lungs,[3,4] knee, fallopian tube and ovary, and intrahepatic portal vein. Surprisingly, pulse granuloma has not been reported in the gastrointestinal tract.
The microscopic features of pulse granuloma evoke a differential diagnosis that includes infectious agents as well as inflammatory and vascular diseases.
The spherical structures containing calcified basophilic granules could potentially be mistaken for fungal forms, such as Coccidioides, but the endospores of Coccidioides are consistently 2 to 4 [micro]m in diameter, whereas the basophilic granules of pulse granuloma vary greatly in size (2-40 [micro]m).