Dados do Trabalho

Título

PRESENCE OF SOMATOSTATIN RECEPTORS IN GRANULOMATOUS DISEASE

Apresentação do caso

A 55-year-old man was hospitalized due to fever and abdominal pain. There were no diarrhea, weight loss or flushing symptoms. As preexisting medical conditions, he had ankylosing spondylitis and was on infliximab for at least 6 months before the first visit.
Abdominal CT scan was performed and an expansive formation close to the midline was visualized. MRI showed rigid and thickened aspecto f the ileal loop, extending for 3.8 cm, a lesion located at the mesentery root measuring 5.4x3.3x3cm, and mesentery, retroperitoneal and periportal lymph node enlargement.
Due to the suspicion of a neuroendocrine tumor, PET/CT with DOTATOC-68Ga (somatostatin analogue) was chosen. There was uptake in ileal thickening and in lymphnodes located in the mesentery root, pericaval, interaortocaval, para-aortic, subcarinal and mediastinal, with a maximum SUV of 6.4. Possibility of mixed tumor due to low SUV was raised and PET/CT with FDG was performed, which confirmed increased uptake in the previously described sites, but with higher SUV, and addition of uptake in peritoneal micronodular lesions and diffusely in the spleen, that were not seen in the PET/CT DOTA.
The patient underwent diagnostic laparoscopy with the finding of diffuse miliary-pattern peritoneal disease. Histopathology showed the presence of a chronic granulomatous inflammatory process. Treatment for tuberculosis (TB) is being started.

Discussão

Well-differentiated neuroendocrine tumors express somatostatin receptors and can be visualized in exams using radiopharmaceuticals labeled with somatostatin analogues. Expression of these receptors can also be seen in activated lymphocytes and macrophages, as it happens in granulomatous diseases such as TB, sarcoidosis and Wegener's granulomatosis, generating false-positive results. Therefore, it is important to always take this differential diagnosis into account, especially in areas with a higher chance of false-positive (such as hilar lymph nodes). Histopathological examination differentiates between the presence of neoplasia and granulomatous disease. However, the diagnosis of extrapulmonary TB is sometimes difficult due to its paucibacillary nature. The finding of granuloma in a country with a high incidence of tuberculosis, such as Brazil, strongly suggests the diagnosis of this infection.

Comentários finais

The expression of somatostatin receptors in granulomatous diseases is an important differential diagnosis when we use tests with radiopharmaceuticals labeled for somatostatin receptors.

Palavras-chave

somatostatin receptors;tuberculosis;PET/CT with DOTATOC-68Ga