Granular cell tumour of the appendix: an unexpected location

© BMJ Publishing Group Limited 2022. No commercial reuse. See rights and permissions. Published by BMJ. DESCRIPTION Granular cell tumour (GCT) is an uncommon but usually benign lesion of neural/Schwann origin. This tumour type is most frequently found in skin, subcutaneous tissue and oral cavity, mostly in black middleaged women. This lesion type can involve any organ, including the gastrointestinal (GI) tract. The appendicular involvement though is extremely rare. We report a case of a pregnant female patient in her early 30s who went to the emergency department after 2 days of enduring persistent pelvic pain. The blood tests indicated leucocytosis, neutrophilia and elevated C reactive protein concentration. Abdominal ultrasound examination revealed an outer appendiceal diameter of 8 mm, with a markedly thickened and stratified wall. The increased density of the surrounding fat tissue was consistent with phlegmon. A laparoscopic appendectomy was performed. Careful gross examination showed that the appendix was increased in size, the appendiceal wall was markedly thickened and the lumen filled with faecal material. The complete histological analysis of the specimen revealed a wellcircumscribed and unencapsulated nodule with 0.5 cm in diameter confined to the submucosa. There was also a florid granulomatous chronic inflammation measuring 1.2 cm extending to the tip of the appendix (as shown in figure 1A). This granulomatous inflammation was located in the wall and involved its entire thickness, except the overlying mucosa. The multiple, coalescent microgranulomas (nonnecrosing granulomas) were composed only of epithelioid histiocytes. The authors want to emphasise that there was no clinical or imaging procedure of the thorax, which may constitute evidence for tuberculosis diagnosis. The surrounding tissues showed reactive and hyperplastic mucosa, with no atrophy. There were no acute appendicitis lesions. The nodule was composed of nests of epithelioid cells with abundant granular eosinophilic cytoplasm and central small round nuclei (as shown in figure 1C). The tumour was devoid of cytological atypia and necrosis. Immunohistochemistry revealed S100 protein strong and diffuse positivity, suggestive of Schwann cell origin, and it was not expressed by the granulomatous epithelioid cells. The GCT cells also displayed SOX10 nuclear expression (as shown in figure 1D) and CD68 membrane expression. CD68