KEYWORDS
Renal cell carcinoma, Succinate dehydrogenase, Ultrasonography, Computed tomography, Magnetic resonance imaging, Pathology
Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) is a malignant epithelial tumor defined by the absence of immunohistochemical expression of mitochondrial complex II. Due to its incidence accounting for only 0.05% to 0.2% of all renal carcinomas, SDH-deficient RCCs are always misdiagnosed or escape diagnosis.1 Here, we report a case of SDH-deficient RCC characterized by ultrasonography, computed tomography, and magnetic resonance imaging as well as confirmed by pathological examination.
A 50-year-old man was admitted to our hospital with polypnea for 1 month and smoking for 30 years. He had a history of hypertension and hepatitis B confirmed recently. After admission, abdominal ultrasonography revealed a cystic-solid mass located in the left kidney (Figure 1). Then, computed tomography of the abdomen was performed to describe the mass (Figure 2). Furthermore, magnetic resonance imaging provided more characteristics of this mass (Figure 3). Eventually, the patient underwent surgical resection, and a pathological diagnosis of SDH-deficient RCC was confirmed (Figure 4). Immunohistochemical staining showed that CK, CK8/18, Vim, PAX-8, GATA3, HNF1 Beta were positive and AMACR, TFE-3, E-Cad were partly positive as well as CK7, CK20, RCC, CA, IX, CD10, CD117, 34BetaE12, SDHB were negative. Ki-67 was approximately 30%.
SDH-deficient RCCs tend to occur in relatively young adults with a mean age of 38 years and the male-to-female ratio is 1.8. Most of them were unilateral or bilateral, while others could be combined with paragangliomas, gastrointestinal stromal tumors, or pituitary adenomas.2 Regarding the imaging of SDH-deficient RCCs, abdominal ultrasound shows that the masses are oval, well-defined, and mix-echoic with or without blood flow signals. Computed tomography and magnetic resonance imaging revealed that the masses could be cystic, cystic–solid, or solid with obvious enhancement.1Fortunately, most SDH-deficient RCCs have a favorable prognosis for low metastatic risk with low nuclear grade after nephron-sparing surgery. However, others have more aggressive progression for a higher metastatic rate with coagulative necrosis, high nuclear grade, or sarcomatoid dedifferentiation, and radical nephrectomy should be performed.3