title: Leydig cell tumor of the testis with histological and immunohistochemical features of malignancy in a 1-year-old boy with isosexual pseudoprecocity.
abstract: The article reports the clinical, histopathological, and immunohistochemical findings of a 1-year-old boy presenting with isosexual pseudoprecocity attributable to a functioning Leydig cell tumor of the testis. The case appears to represent the youngest patient ever recognized with this well-known syndrome. Malignancy features were also for the first time initially assessed using criteria, retrospectively developed from the literature, for metastasizing Leydig cell tumor. All the following were found: infiltrative borders, cellular pleomorphism, high mitotic index (12-14/high-power field), high MIB-1 index (40%), P53 positivity in 50% of the cells, and bcl-2 positivity in 15% of the cells. Immunohistochemistry proved the cells of the tumor to be positive for inhibin, Melan-A, synaptophysin, cytokeratin, and calretinin and negative for S-100 and chromogranin A. Notably, lipochrome and crystals of Reinke were not found in the tumor cells. Although the neoplasm fulfilled the criteria for a potentially metastasizing Leydig cell tumor, there was no evidence of that event having occurred, perhaps as a result of early treatment or as indication that criteria developed for Leydig cell tumor of adults may not apply to children.
authors.affiliation: Consultoria em Patologia, Botucatu, Sao Paulo, Brazil. patologi@netverk.com.ar
authors.forename: Ricardo
authors.initials: R
authors.lastname: Drut
authors.forename: Sheila
authors.initials: S
authors.lastname: Wludarski
authors.forename: Vanderlei
authors.initials: V
authors.lastname: Segatelli
authors.forename: Ebe
authors.initials: E
authors.lastname: de Oliveira
authors.forename: Ana
authors.initials: A
authors.lastname: Barbosa
authors.forename: Andre
authors.initials: A
authors.lastname: Matheus
authors.forename: Carlos
authors.initials: C
authors.lastname: Bacchi
mesh_terms: D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism; D064032:Calbindin 2; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007265:Inhibins / Q000235:genetics / Q000378:metabolism; D007633:Keratins / Q000235:genetics / Q000378:metabolism; D007984:Leydig Cell Tumor / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D058965:MART-1 Antigen; D008297:Male; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D011629:Puberty, Precocious / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D064030:S100 Calcium Binding Protein G / Q000235:genetics / Q000378:metabolism; D016708:Synaptophysin / Q000235:genetics / Q000378:metabolism; D013736:Testicular Neoplasms / Q000150:complications / Q000378:metabolism / Q000473:pathology*
chemical_list: D000951:Antigens, Neoplasm; C576764:CALB2 protein, human; D064032:Calbindin 2; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins; D064030:S100 Calcium Binding Protein G; D016708:Synaptophysin; D007265:Inhibins; D007633:Keratins