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