{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T09:09:17Z","timestamp":1788858557971,"version":"build-2803163510"},"reference-count":21,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T00:00:00Z","timestamp":1788825600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Clin. Med.","JCM"],"abstract":"<jats:p>Background: Pheochromocytoma is a rare tumor of the adrenal medulla, often associated with hypertension, headache, diaphoresis, and palpitations, but presentations vary; some are silent until incidentally found or when complications develop. One rare complication is spontaneous adrenal hemorrhage, previously mainly found at autopsy, which can extend into the retroperitoneum, causing acute pain and mimicking emergencies. Imaging modalities like computed tomography are vital for detection, especially in acute cases, while magnetic resonance imaging provides greater tissue detail to identify tumors such as pheochromocytomas. If a functional adrenal tumor is suspected, biochemical tests for catecholamine excess are crucial for diagnosis and management. In this report, we present a case of pheochromocytoma that initially manifested with spontaneous adrenal hemorrhage without hypertension, thereby complicating and prolonging the diagnostic process. Case presentation: A previously healthy 34-year-old man presented with sudden, severe right-sided abdominal and flank pain, nausea, vomiting, and headache. He was normotensive but anemic and required a red blood cell transfusion. Initial computed tomography revealed a large hemorrhagic lesion in the right retroperitoneal space. The hematoma was managed conservatively. Magnetic resonance imaging confirmed subacute hematoma. Follow-up computed tomography showed gradual regression of the hematoma but persistence of an enhancing right adrenal lesion. Elevated plasma metanephrine and normetanephrine levels, together with positive iodine-123 metaiodobenzylguanidine imaging and preoperative computed tomography, supported the diagnosis of pheochromocytoma. After preoperative alpha-adrenergic blockade, laparoscopic right adrenalectomy was performed without complications. Histopathology confirmed a pheochromocytoma classified as moderately differentiated (GAPP), with a Ki-67index of 1\u20133%. Genetic testing showed no pathogenic variants in the analyzed genes associated with hereditary pheochromocytoma or paraganglioma syndromes. Conclusions: Spontaneous adrenal hemorrhage may be the first sign of pheochromocytoma, even in normotensive patients. Acute bleeding can obscure the tumor. Persistent adrenal lesions after hematoma regression should be monitored with computed tomography or magnetic resonance imaging, along with biochemical and functional evaluation, to avoid serious complications or death.<\/jats:p>","DOI":"10.3390\/jcm15186938","type":"journal-article","created":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T08:10:22Z","timestamp":1788855022000},"page":"6938","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Pheochromocytoma Presenting as Spontaneous Adrenal Hemorrhage in a Normotensive Patient: A Case Report"],"prefix":"10.3390","volume":"15","author":[{"given":"Jok\u016bbas","family":"Ramanauskas","sequence":"first","affiliation":[{"name":"Medical Academy, Lithuanian University of Health Sciences, 44307 Kaunas, Lithuania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9150-0681","authenticated-orcid":false,"given":"Vestina","family":"Strak\u0161yt\u0117","sequence":"additional","affiliation":[{"name":"Department of Radiology, Medical Academy, Lithuanian University of Health Sciences, 44307 Kaunas, Lithuania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Inga","family":"Zaborien\u0117","sequence":"additional","affiliation":[{"name":"Department of Radiology, Medical Academy, Lithuanian University of Health Sciences, 44307 Kaunas, Lithuania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kristina","family":"\u017dvinien\u0117","sequence":"additional","affiliation":[{"name":"Department of Radiology, Medical Academy, Lithuanian University of Health Sciences, 44307 Kaunas, Lithuania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Milda","family":"Jasevi\u010d\u0117","sequence":"additional","affiliation":[{"name":"Department of Radiology, Medical Academy, Lithuanian University of Health Sciences, 44307 Kaunas, Lithuania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"bvac105","DOI":"10.1210\/jendso\/bvac105","article-title":"Systematic review: Incidence of pheochromocytoma and paraganglioma over 70 years","volume":"6","author":"Boyle","year":"2022","journal-title":"J. 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