Endocrine Abstracts

JOINT1959

Introduction.: Adrenal schwannoma (AS) is a rare, typically benign tumor originating from Schwann cells, often found in the adrenal medulla. Peri-adrenal (peri-AS) or juxta-adrenal schwannomas originate from tissues surrounding the adrenal gland. Despite their anatomical differences, they share similarities with AS in clinical presentation, management, and histopathological features. There are fewer than 200 reported cases of AS and peri-AS, highlighting their rarity. We report two cases, one of adrenal and one of peri-adrenal schwannoma.

Case 1.: A 50-year-old female presented with an adrenal incidentaloma discovered during an MRI for uterine fibroids. CT imaging of the adrenals confirmed the 6 cm mainly cystic lesion with septa of her right adrenal compressing the inferior vena cava. Her past medical history was unremarkable and hormonal workup was normal. She underwent open surgery and a 6x5.5x4.5 cm lesion weighing 85 g was excised and its histopathological examination revealed alternating Antoni A and Antoni B areas, necrosis, hemorrhage, strongly and diffusely positive S100 immunomarker and a Ki67 index of 3%. Immunohistochemistry confirmed AS. Four years post-surgery, follow-up imaging showed no recurrence.

Case 2.: A 62-year-old female presented with an adrenal incidentaloma detected on abdominal ultrasound for abdominal pain. Her past medical history was unremarkable. CT imaging of her adrenals revealed a 4x3.2x3 cm right adrenal lesion with 61.2 HU, which on MRI was heterogenous with no intracellular fat. Hormonal workup was normal. She underwent surgery and an 78 g, 4.5x3.5x3 cm mass was removed from her right adrenal. Histopathological examination revealed hemorrhages, necrosis, and degenerative changes. Immunohistochemistry confirmed the diagnosis of schwannoma (positive for S100 and SOX10; negative for synaptophysin).

Conclusion: AS and peri-AS are rare tumors often presenting as non-functional masses, with diagnosis confirmed through histopathological examination following surgical removal. They can be discovered incidentally on imaging for unrelated issues. Pre-operative diagnosis is challenging due to their asymptomatic or nonspecific presentation (abdominal or back pain from adjacent organ compression) and on imaging is difficult to differentiate them from other adrenal or peri-adrenal masses. Surgery (adrenalectomy/removal of the peri-AS tumor) is essential to confirm diagnosis and exclude malignancy. Their histopathological findings of encapsulated spindle cell tumors, nuclear atypia, cystic changes, and hemorrhage, complicate the diagnosis. The S100 immunomarker is typically strongly and diffusely positive and a key feature in supporting schwannoma diagnosis.