A 33-year-old woman consulted for abdominal pain of two months' duration located in the right iliac fossa with no other accompanying symptoms. The patient visited several hospitals, where she was discharged with normal basic complementary tests. She attended the emergency department of our hospital due to the persistence of her symptoms.
An abdominal Doppler ultrasound was performed, showing a hypervascularised nodule measuring one centimetre in diameter in the right iliac fossa. The patient was admitted to our department with the diagnostic presumption of endometrioma in order to complete the studies. The CT scan performed during admission revealed a single nodule measuring 1 x 1.5 cm located in the appendix.
The patient underwent an exploratory laparoscopy which identified the appendix with no inflammatory signs and the nodule described above. Anatomopathological examination of the removed specimen revealed macroscopically a hard nodule at the tip of the appendix, which was reported as a granular cell tumour. The lesion extends into the subserosal adipose tissue of the appendix.

Histologically, the proliferating cell is medium to large with a large cytoplasm and small nuclei with a patent nucleolus and prominent eosinophilic granules in the cytoplasm. Immunohistochemical techniques show positivity for S100 protein.

Once the histological diagnosis was known, upper and lower gastrointestinal endoscopies were performed, which did not detect any other lesions.