{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T00:03:22Z","timestamp":1782173002001,"version":"3.54.5"},"reference-count":16,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2025,11,25]],"date-time":"2025-11-25T00:00:00Z","timestamp":1764028800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Uterine angiomyolipoma (AML) is an exceptionally rare mesenchymal tumor of the perivascular epithelioid cell tumor (PEComa) family. Most cases are benign and exhibit a triphasic histologic pattern. Although extragenital PEComas typically show strong, diffuse HMB-45 reactivity, uterine AMLs\/PEComas often exhibit weak or negative staining, thereby introducing diagnostic uncertainty. We describe a rare case of uterine AML with diffuse nuclear atypia in a postmenopausal woman, which mimicked a degenerative leiomyoma or leiomyosarcoma. A 49-year-old postmenopausal woman presented with the rapid enlargement of a uterine mass that had been followed for four years as a presumed leiomyoma. Imaging revealed a well-circumscribed uterine mass with heterogeneous enhancement, cystic degeneration, and restricted diffusion on MRI. A total hysterectomy was performed. Grossly, the tumor measured 8 cm. Microscopically, it consisted of pleomorphic epithelioid cells (70%), mature adipose tissue (20%), and thick-walled vessels. Immunohistochemistry revealed diffuse smooth muscle actin (SMA) positivity, while Human Melanoma Black (HMB)-45 and Melan-A were negative. Only one mitosis per 50 HPF was identified, with no atypical mitoses or necrosis, and the Ki-67 index was low (&lt;5%). The patient has remained disease-free for 56 months post-surgery. This case represents the first documented HMB-45-negative uterine angiomyolipoma with diffuse nuclear atypia, characterized by a low mitotic index, low Ki-67 proliferation rate, and a benign 56-month follow-up. It broadens the morphologic spectrum of uterine AML, demonstrating that diffuse nuclear atypia can occur in HMB-45-negative tumors with benign behavior, and that atypia alone should not be interpreted as evidence of malignancy. Recognition of this rare variant is essential to avoid misdiagnosing it as leiomyosarcoma.<\/jats:p>","DOI":"10.3390\/diagnostics15232995","type":"journal-article","created":{"date-parts":[[2025,11,25]],"date-time":"2025-11-25T15:29:47Z","timestamp":1764084587000},"page":"2995","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Uterine Angiomyolipoma Presenting as a Rapidly Growing Uterine Mass in a Postmenopausal Woman"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7163-0403","authenticated-orcid":false,"given":"Dae Hyun","family":"Song","sequence":"first","affiliation":[{"name":"Department of Pathology, Institute of Health Science, School of Medicine, Gyeongsang National University, Jinju 52727, Republic of Korea"},{"name":"Department of Pathology, Gyeongsang National University Changwon Hospital, Changwon 51472, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyo Jung","family":"An","sequence":"additional","affiliation":[{"name":"Department of Pathology, Institute of Health Science, School of Medicine, Gyeongsang National University, Jinju 52727, Republic of Korea"},{"name":"Department of Pathology, Gyeongsang National University Changwon Hospital, Changwon 51472, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jong Chul","family":"Baek","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, Institute of Health Science, School of Medicine, Gyeongsang National University, Jinju 52727, Republic of Korea"},{"name":"Department of Obstetrics and Gynecology, Gyeongsang National University Changwon Hospital, Changwon 51472, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1097\/00004347-200201000-00013","article-title":"Epithelioid angiomyolipoma of the ovary: A case report and literature review","volume":"21","author":"Anderson","year":"2002","journal-title":"Int. J. Gynecol. Pathol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1355","DOI":"10.1038\/modpathol.2013.72","article-title":"Epithelioid angiomyolipoma of the kidney: Pathological features and clinical outcome in a series of consecutively resected tumors","volume":"26","author":"He","year":"2013","journal-title":"Mod. Pathol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1105","DOI":"10.1111\/iju.12117","article-title":"Epithelioid angiomyolipoma of the kidney: Radiological imaging","volume":"20","author":"Tsukada","year":"2013","journal-title":"Int. J. Urol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"341","DOI":"10.3897\/folmed.64.e60937","article-title":"Uterine angiolipoleiomyoma. 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Pathol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1002\/path.2289","article-title":"Constant allelic alteration on chromosome 16p (TSC2 gene) in perivascular epithelioid cell tumour (PEComa): Genetic evidence for the relationship of PEComa with angiomyolipoma","volume":"214","author":"Pan","year":"2008","journal-title":"J. Pathol."}],"container-title":["Diagnostics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4418\/15\/23\/2995\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,11,25]],"date-time":"2025-11-25T15:48:44Z","timestamp":1764085724000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4418\/15\/23\/2995"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,11,25]]},"references-count":16,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2025,12]]}},"alternative-id":["diagnostics15232995"],"URL":"https:\/\/doi.org\/10.3390\/diagnostics15232995","relation":{},"ISSN":["2075-4418"],"issn-type":[{"value":"2075-4418","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,11,25]]}}}