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Abstract：
BACKGROUND: Solitary fibrous tumor (SFT) is a rare fibroblastic mesenchymal tumor that mostly involves the pleura and infrequently involves extra-pleural sites. De novo SFT of the kidney is uncommon, and malignant SFT is extremely rare.
METHODS: We report a case of a 51-year-old man with a large malignant SFT in the left kidney. Pathological examination confirmed the diagnosis of SFT based on typical morphology, nuclear STAT6 expression, and NAB2-STAT6 gene fusion. The malignant subtype was determined by a large tumor size (≥ 15 cm) and high mitotic counts (8/10 high-power fields). KRAS mutation was identified by DNA sequencing. Insulin-like growth factor 2 (IGF2) was diffusely and strongly expressed in tumor cells, however, hypoglycemia was not observed. Hyperglycemia and high adrenocorticotropic hormone (ACTH) concentration were observed one month after surgery. Hormone measurements revealed normal blood cortisol and aldosterone levels, and increased urinary free cortisol level. A pituitary microadenoma was identified using brain magnetic resonance imaging, which may be responsible for the promotion of hyperglycemia.
CONCLUSIONS: We report a case of renal malignant SFT with a KRAS mutation, which was previously unreported in SFT and may be associated with its malignant behavior. Additionally, we emphasize that malignant SFT commonly causes severe hypoglycemia due to the production of IGF2. However, this effect may be masked by the presence of other lesions that promote hyperglycemia. Therefore, when encountering a malignant SFT with diffuse and strong IGF2 expression and without hypoglycemia, other lesions promoting hyperglycemia need to be ruled out.
METHODS: We report a case of a 51-year-old man with a large malignant SFT in the left kidney. Pathological examination confirmed the diagnosis of SFT based on typical morphology, nuclear STAT6 expression, and NAB2-STAT6 gene fusion. The malignant subtype was determined by a large tumor size (≥ 15 cm) and high mitotic counts (8/10 high-power fields). KRAS mutation was identified by DNA sequencing. Insulin-like growth factor 2 (IGF2) was diffusely and strongly expressed in tumor cells, however, hypoglycemia was not observed. Hyperglycemia and high adrenocorticotropic hormone (ACTH) concentration were observed one month after surgery. Hormone measurements revealed normal blood cortisol and aldosterone levels, and increased urinary free cortisol level. A pituitary microadenoma was identified using brain magnetic resonance imaging, which may be responsible for the promotion of hyperglycemia.
CONCLUSIONS: We report a case of renal malignant SFT with a KRAS mutation, which was previously unreported in SFT and may be associated with its malignant behavior. Additionally, we emphasize that malignant SFT commonly causes severe hypoglycemia due to the production of IGF2. However, this effect may be masked by the presence of other lesions that promote hyperglycemia. Therefore, when encountering a malignant SFT with diffuse and strong IGF2 expression and without hypoglycemia, other lesions promoting hyperglycemia need to be ruled out.
摘要：
背景：孤立性纤维性肿瘤（SFT）是一种罕见的成纤维细胞间充质肿瘤，主要累及胸膜，很少累及胸膜外部位。肾脏的从头SFT并不常见，恶性SFT极为罕见。
方法：我们报告了一例51岁的男性，其左肾恶性SFT较大。病理检查根据典型形态学证实SFT的诊断，核STAT6表达，和NAB2-STAT6基因融合。恶性亚型由大肿瘤大小（≥15cm）和高有丝分裂计数（8/10高倍视野）确定。通过DNA测序鉴定KRAS突变。胰岛素样生长因子2（IGF2）在肿瘤细胞中弥漫性强表达，然而,未观察到低血糖.术后1个月观察到高血糖和高促肾上腺皮质激素（ACTH）浓度。激素测量显示血液皮质醇和醛固酮水平正常，和增加尿游离皮质醇水平。使用脑磁共振成像确定了垂体微腺瘤，这可能是促进高血糖的原因。
结论：我们报告一例KRAS突变的肾恶性SFT，以前在SFT中未报道，可能与其恶性行为有关。此外,我们强调,由于IGF2的产生,恶性SFT通常会导致严重的低血糖.然而,这种效应可能被其他促进高血糖的病变掩盖.因此,当遇到具有弥漫性和强IGF2表达且无低血糖的恶性SFT时，其他促进高血糖的病变需要排除.
方法：我们报告了一例51岁的男性，其左肾恶性SFT较大。病理检查根据典型形态学证实SFT的诊断，核STAT6表达，和NAB2-STAT6基因融合。恶性亚型由大肿瘤大小（≥15cm）和高有丝分裂计数（8/10高倍视野）确定。通过DNA测序鉴定KRAS突变。胰岛素样生长因子2（IGF2）在肿瘤细胞中弥漫性强表达，然而,未观察到低血糖.术后1个月观察到高血糖和高促肾上腺皮质激素（ACTH）浓度。激素测量显示血液皮质醇和醛固酮水平正常，和增加尿游离皮质醇水平。使用脑磁共振成像确定了垂体微腺瘤，这可能是促进高血糖的原因。
结论：我们报告一例KRAS突变的肾恶性SFT，以前在SFT中未报道，可能与其恶性行为有关。此外,我们强调,由于IGF2的产生,恶性SFT通常会导致严重的低血糖.然而,这种效应可能被其他促进高血糖的病变掩盖.因此,当遇到具有弥漫性和强IGF2表达且无低血糖的恶性SFT时，其他促进高血糖的病变需要排除.
