Birt‐Hogg‐Dubé syndrome‐associated renal cell carcinoma: Histopathological features and diagnostic conundrum

Birt‐Hogg‐Dubé (BHD) syndrome is associated with the development of hereditary renal cell carcinoma (RCC) and is caused by a germline mutation in the folliculin gene. Most cases of BHD syndrome‐associated RCC (BHD‐RCC) are less aggressive than sporadic clear cell RCC and multifocal. Therefore, it is critical to distinguish BHD‐RCC from its sporadic counterparts to identify and monitor affected families and to preserve renal function for as long as possible. The World Health Organization/International Society of Urological Pathology consensus classification defined distinct entities for certain hereditary RCC; however, BHD‐RCC was not included in this classification. Although the clinical features and molecular mechanisms of BHD‐RCC have been investigated intensively over the last two decades, pathologists and urologists occasionally face difficulties in the diagnosis of BHD‐RCC that require genetic testing. Affected patients usually have miscellaneous benign disorders that often precede renal carcinogenesis. In the present review, we summarize the current understanding of the histopathological features of BHD‐RCC based on our epidemiological studies of Japanese families and a literature review. Pathological diagnostic clues and differential diagnosis of BHD‐RCC from other hereditary RCC are also briefly discussed.     

Agminated fibroblastic connective tissue nevus in a 1‐year‐old boy

Fibroblastic connective tissue nevus (FCTN) is a benign cutaneous mesenchymal lesion characterized by proliferation of CD34‐positive fibroblastic/myofibroblastic spindle‐shaped cells. We report a case of agminated FCTN on the right lower abdomen of a 1‐year‐old boy.     

Differentiation inducing effects of vesnarinone on human glioma cells

The effects of 3,4-dihydro-6-[4-(3,4-dimethoxybenzoyl)-1-piperazinyl]-2(1H)-quinolinone (vesnarinone) on the growth of glioma cells were examined in vitro. Vesnarinone at a dose of 100 mug/ml suppressed the growth of four different glioma cell lines, U-251MG, U-373MG, U-87MG and A-172, by approximately 50%, with an elongation of the cytoplasmic process on day 5 of culture. The long-term culture of U-87MG with 10 mug/ml of vesnarinone was continued up to day 34. Although growth suppression was approximately 25% on day 5, it reached over 95% on day 34. An increase in the cyclic adenosine monophosphate content of glioma cells cultured with vesnarinone was observed by enzyme-linked immunosorbent assay (ELISA). The accumulation of glial fibrillary acidic protein was observed to occur with vesnarinone by ELISA. These findings suggest that vesnarinone suppressed the growth and induced differentiation of glioma cells in vitro.     

Pressure overload-induced transient oxidative stress mediates perivascular inflammation and cardiac fibrosis through angiotensin II.

Oxidative stress is implicated in the pathogenesis of various cardiovascular diseases. We have shown that in Wistar rats with a suprarenal aortic constriction (AC), pressure overload-induced transient perivascular inflammation (monocyte chemoattractant protein-1 [MCP-1] induction and macrophage accumulation) in the early phase is the determinant of reactive myocardial fibrosis and resultant diastolic dysfunction in the late phase. Thus, we investigated the role of reactive oxygen species production in cardiac remodeling in AC rats. Superoxide production and the footprint of lipid peroxidation were assessed using dihydroethidium staining and immunohistostaining against 4-hydroxy-2-nonenal (4-HNE), respectively. In sham rats, dihydroethidium and 4-HNE signals were scarcely found in the heart. At day 3, AC rats showed dihydroethidium signals mainly in the intramyocardial arterial wall, whereas modest 4-HNE staining was observed diffusely in the myocardium. These signals declined to lower levels by day 14 despite sustained hypertension. Chronic administration of a subdepressor dose of an angiotensin II type 1 receptor blocker candesartan reduced the pressure overload-induced dihydroethidium and 4-HNE signals at day 3. Moreover, candesartan decreased MCP-1 induction and macrophage infiltration at day 3 and prevented myocardial fibrosis at day 14, without affecting left ventricle and myocyte hypertrophy. In conclusion, acute pressure overload induced self-limited superoxide production mainly in the vascular wall. The reactive oxygen species production would contribute to the perivascular inflammation and subsequent myocardial fibrosis. Angiotensin II was suggested to have a pressure-independent effect on the reactive oxygen species production.     

Increased expression of gp91phox homologues of NAD(P)H oxidase in the aortic media during chronic hypertension: involvement of the renin-angiotensin system.

Although vascular cells express multiple members of the Nox family of nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase, including gp91phox, Nox1, and Nox4, the reasons for the different expressions and specific roles of these members in vascular injury in chronic hypertension have remained unclear. Thus, we quantified the mRNA expressions of these NAD(P)H oxidase components by real-time polymerase chain reaction and evaluated superoxide production and morphological changes in the aortas of 32-week-old stroke-prone spontaneously hypertensive rats (SHRSP) and age-matched Wistar Kyoto rats (WKY). The aortic media of SHRSP had an approximately 2.5-fold greater level of Nox4 mRNA and an approximately 10-fold greater level of Nox1 mRNA than WKY. The mRNA expressions of gp91phox and p22phox in SHRSP and WKY were comparable. SHRSP were treated from 24 weeks of age for 8 weeks with either high or low doses of candesartan (4 mg/kg/day or 0.2 mg/kg/day), or a combination of hydralazine (30 mg/kg/day) and hydrochlorothiazide (4.5 mg/kg/day). The high-dose candesartan or the hydralazine plus hydrochlorothiazide decreased the blood pressure of SHRSP to that of WKY, whereas the low-dose candesartan exerted no significant antihypertensive action. Media thickening and fibrosis, as well as the increased production of superoxide in SHRSP, were nearly normalized with high-dose candesartan and partially corrected with low-dose candesartan or hydralazine plus hydrochlorothiazide. These changes by antihypertensive treatment paralleled the decrease in mRNA expression of Nox4 and Nox1. These results suggest that blood pressure and angiotensin II type 1 receptor activation are involved in the up-regulation of Nox1 and Nox4 expression, which could contribute to vascular injury during chronic hypertension.     

PEUTZ‐JEGHERS SYNDROME ASSOCIATED WITH RENAL AND GASTRIC CANCER THAT DEMONSTRATED AN STK11 MISSENSE MUTATION

A 75‐year‐old male was admitted to the gastroenterology unit of Nagoya City University Hospital due to epigastralgia after surgical treatment for right renal cancer. Endoscopy revealed advanced type 1 gastric cancer in the corpus of the stomach and multiple polypoid lesions in the stomach and duodenum. X‐ray examination of the small intestine using barium showed multiple polyps in the upper jejunum. Faint pigmentation on the palm was also detected. Peutz‐Jeghers syndrome (PJS) was diagnosed, despite a lack of family history. Total gastrectomy, resection of part of the upper jejunum and intraoperative endoscopic polypectomy of duodenal polyps was performed. This is the second reported case of PJS associated with renal cancer. We also detected a missense mutation in the tumor suppressor gene STK11 that, when mutated, is causative for PJS.