Yolk sac tumor of postpubertal-type does not exhibit immunohistochemical loss of SMARCB1/INI1 and SMARCA4/BRG1…but choriocarcinoma?

Ricci, Costantino; Ambrosi, Francesca; Franceschini, Tania; Giunchi, Francesca; Franchini, Eugenia; Massari, Francesco; Mollica, Veronica; Colecchia, Maurizio; Acosta, Andrés M; Fiorentino, Michelangelo

doi:10.1016/j.prp.2022.154269

Cited by 1 publication

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“…All cases had been diagnosed according to the 5th edition of the WHO classification of urinary and male genital tumours 19 . All the cases in this cohort have been previously published by our group 20–22 …”

Section: Methodsmentioning

confidence: 99%

FoxA2 is a reliable marker for the diagnosis of yolk sac tumour postpubertal‐type

Ricci,

Ambrosi,

Franceschini

et al. 2023

Histopathology

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AimsYolk sac tumour postpubertal‐type (YSTpt) shows a wide range of histological patterns and is challenging to diagnose. Recently, forkhead box transcription factor A2 (FoxA2) emerged as a driver of YSTpt formation and a promising marker for diagnosing YSTpt. However, FoxA2 has not been tested in the different patterns of YSTpt. This study aimed to assess the staining pattern of FoxA2 in te different patterns of YSTpt and other germ cell tumours of the testis (GCTT), comparing it with glypican‐3 (GPC3) and α‐fetoprotein (AFP).Methods and resultsFOXA2, GPC3 and AFP immunohistochemistry was performed on 24 YSTpt (24 microcystic/reticular, 10 myxoid, two macrocystic, five glandular/alveolar, two endodermal sinus/perivascular, four solid, two polyembryoma/embryoid body and two polyvesicular vitelline) and 81 other GCTT. The percentage of positive cells (0, 1+, 2+, 3+) and the intensity (0, 1, 2, 3) were evaluated regardless of and within each YSTpt pattern. FoxA2 was positive in all YSTpt (24 of 24) and all but one (23 of 24) exhibited 2+/3+ stain, with higher intensity [median value (mv): 2.6] than AFP (1.8) and GPC3 (2.5). Both FoxA2 and GPC3 were positive in all microcystic/reticular (24 of 24), myxoid (10 of 10), macrocystic (two of two), endodermal sinus/perivascular (four of four) and polyembryoma/embryoid body (two of two) patterns. Nevertheless, only FoxA2 was positive in all glandular/alveolar (five of five), solid (four of four) and polyvesicular vitelline (two of two) patterns. The intensity of FoxA2 was higher than AFP and GPC3 in almost all YST patterns. In the other GCTT, FoxA2 was positive only in teratoma postpubertal‐type (Tpt) [13 of 20 (65%)], with staining almost exclusively confined to the mature gastrointestinal/respiratory tract epithelium.ConclusionsFoxA2 is a highly sensitive and specific biomarker that supports the diagnosis of YSTpt. FoxA2 is superior to GPC3 and AFP, especially in rare and difficult‐to‐diagnose histological patterns of YSTpt, but mature glands of Tpt could represent a potential diagnostic pitfall.

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Section: Methodsmentioning

confidence: 99%