{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T18:13:54Z","timestamp":1779905634545,"version":"3.53.1"},"reference-count":6,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2021,3,31]],"date-time":"2021-03-31T00:00:00Z","timestamp":1617148800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Histopathology"],"published-print":{"date-parts":[[2021,6]]},"abstract":"<jats:sec><jats:title>Aims<\/jats:title><jats:p>Perivascular epithelioid cell tumours (PEComas) of the appendix have been reported very rarely. In this study, we describe three cases of a distinctive micronodular proliferation in the appendix consistent with a variant of PEComa. Although known as \u2018granular degeneration of smooth muscle\u2019 in prior reports, we reappraise its clinicopathological, immunohistochemical and ultrastructural features which support a change in classification.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods and results<\/jats:title><jats:p>Patients were two females (aged 33 and 41\u00a0years) and one male (aged 41). None had a history of tuberous sclerosis. Histologically, each case demonstrated a multifocal nodular proliferation towards the distal tip of the appendix, composed of epithelioid cells with abundant granular eosinophilic to clear cytoplasm. By immunohistochemistry, the lesional cells were positive for muscle markers [smooth muscle actin (SMA) and desmin], melanocytic markers (HMB45, melan A), cathepsin K and the lysosomal marker NKI\u2010C3 in each case. MITF was positive in two of three cases. None expressed S100 protein. Electron microscopy in one case revealed striated electron\u2010dense structures consistent with pre\u2010melanosomes. Follow\u2010up, available in one case, showed no recurrence at 5\u00a0years.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>We propose the term \u2018micronodular PEComa\u2019 for this appendiceal lesion to reflect more accurately its histological and immunohistochemical characteristics, which include consistent positivity for both muscle and melanocytic markers. Micronodular PEComa seems to follow an indolent course, consistent with its uniformly low\u2010grade histological features, and appears to be unassociated with tuberous sclerosis.<\/jats:p><\/jats:sec>","DOI":"10.1111\/his.14341","type":"journal-article","created":{"date-parts":[[2021,1,27]],"date-time":"2021-01-27T13:34:02Z","timestamp":1611754442000},"page":"1047-1050","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Micronodular PEComas of the appendix"],"prefix":"10.1111","volume":"78","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5807-7831","authenticated-orcid":false,"given":"William J","family":"Anderson","sequence":"first","affiliation":[{"name":"Department of Pathology Brigham and Women\u2019s Hospital Harvard Medical School Boston MA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nika","family":"Kojc","sequence":"additional","affiliation":[{"name":"Faculty of Medicine Institute of Pathology University of Ljubljana Ljubljana Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8053-9537","authenticated-orcid":false,"given":"Christopher D M","family":"Fletcher","sequence":"additional","affiliation":[{"name":"Department of Pathology Brigham and Women\u2019s Hospital Harvard Medical School Boston MA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6475-8345","authenticated-orcid":false,"given":"Jason L","family":"Hornick","sequence":"additional","affiliation":[{"name":"Department of Pathology Brigham and Women\u2019s Hospital Harvard Medical School Boston MA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2021,3,31]]},"reference":[{"key":"e_1_2_7_2_1","doi-asserted-by":"publisher","DOI":"10.1053\/j.semdp.2004.11.006"},{"key":"e_1_2_7_3_1","doi-asserted-by":"publisher","DOI":"10.1177\/106689690000800112"},{"key":"e_1_2_7_4_1","doi-asserted-by":"publisher","DOI":"10.1097\/00000478-199606000-00010"},{"key":"e_1_2_7_5_1","first-page":"427","article-title":"Granular degeneration of appendiceal smooth muscle","volume":"92","author":"Sobel HJ","year":"1971","journal-title":"Arch. Pathol."},{"key":"e_1_2_7_6_1","doi-asserted-by":"publisher","DOI":"10.1177\/1066896920922589"},{"key":"e_1_2_7_7_1","doi-asserted-by":"publisher","DOI":"10.1097\/PAS.0b013e31829caab3"}],"container-title":["Histopathology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1111\/his.14341","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1111\/his.14341","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1111\/his.14341","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,9,1]],"date-time":"2023-09-01T13:48:04Z","timestamp":1693576084000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/his.14341"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,3,31]]},"references-count":6,"journal-issue":{"issue":"7","published-print":{"date-parts":[[2021,6]]}},"alternative-id":["10.1111\/his.14341"],"URL":"https:\/\/doi.org\/10.1111\/his.14341","archive":["Portico"],"relation":{},"ISSN":["0309-0167","1365-2559"],"issn-type":[{"value":"0309-0167","type":"print"},{"value":"1365-2559","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,3,31]]},"assertion":[{"value":"2021-01-21","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2021-01-23","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2021-03-31","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}