Stephen M. Lagana

Mutation in Glycerol-3-Phosphate Dehydrogenase 1–Like Gene (GPD1-L) Decreases Cardiac Na+ Current and Causes Inherited Arrhythmias

Background— Brugada syndrome is a rare, autosomal-dominant, male-predominant form of idiopathic ventricular fibrillation characterized by a right bundle-branch block and ST elevation in the right precordial leads of the surface ECG. Mutations in the cardiac Na+ channel SCN5A on chromosome 3p21 cause ≈20% of the cases of Brugada syndrome; most mutations decrease inward Na+ current, some by preventing trafficking of the channels to the surface membrane. We previously used positional cloning to identify a new locus on chromosome 3p24 in a large family with Brugada syndrome and excluded SCN5A as a candidate gene. Methods and Results— We used direct sequencing to identify a mutation (A280V) in a conserved amino acid of the glycerol-3-phosphate dehydrogenase 1–like (GPD1-L) gene. The mutation was present in all affected individuals and absent in >500 control subjects. GPD1-L RNA and protein are abundant in the heart. Compared with wild-type GPD1-L, coexpression of A280V GPD1-L with SCN5A in HEK cells reduced inward Na+ currents by ≈50% (P<0.005). Wild-type GPD1-L localized near the cell surface to a greater extent than A280V GPD1-L. Coexpression of A280V GPD1-L with SCN5A reduced SCN5A cell surface expression by 31±5% (P=0.01). Conclusions— GPD1-L is a novel gene that may affect trafficking of the cardiac Na+ channel to the cell surface. A GPD1-L mutation decreases SCN5A surface membrane expression, reduces inward Na+ current, and causes Brugada syndrome.

Coronary artery aneurysm: a review and hypothesis regarding etiology.

CONTEXT Coronary artery aneurysm is an uncommon condition that can be a cause of death when it thromboses or ruptures. It is always associated with destruction of the tunica media, usually associated with atherosclerosis, and commonly associated with chronic inflammation. OBJECTIVE To review the pathology, epidemiologic and clinical features, and pathophysiology of coronary artery aneurysm, particularly new research results, drawing out implications for the understanding, diagnosis, and treatment of this condition. DATA SOURCES Pertinent literature and illustrative cases at our institution. CONCLUSIONS Inflammation spilling over into the tunica media from the tunica intima may link atherosclerosis to aneurysm formation, but vasculitis without atherosclerosis causes coronary artery aneurysms in young children with Kawasaki disease. Increased proteolysis of extracellular matrix proteins is probably one mechanism of coronary artery aneurysm formation, either due to overactive matrix metalloproteinases or underactive inhibition of these proteinases, and an excess of transforming growth factor beta may be another mechanism in the pathogenesis. Coronary atherosclerosis is a universal disease of adults, but only 1.5% of them have coronary aneurysms; this small group may be those with a second coronary artery disease, such as vasculitis.

Utility of an immunohistochemical panel consisting of glypican-3, heat-shock protein-70, and glutamine synthetase in the distinction of low-grade hepatocellular carcinoma from hepatocellular adenoma.

Background:The pathologic distinction between hepatocellular carcinoma (HCC) and hepatocellular adenoma (HCA) is sometimes problematic due to histologic overlap between the 2 entities, a problem amplified on small biopsy specimens. Several recently characterized immunohistochemical markers such as glypican-3 (GPC-3), heat-shock protein-70 (HSP-70), and glutamine synthetase (GS) help distinguish dysplastic nodules from HCC. The utility of this panel in the distinction of low-grade hepatocellular carcinoma (LG-HCC) from HCA has not been fully described. Objective:To determine whether the above markers are useful in the distinction of HCCs from HCAs. Design:Tissue microarrays were constructed with 30 LG-HCCs and 18 HCAs. The arrays were stained with the above markers and analyzed with respect to amount and pattern of staining. GPC-3 and HSP-70 were considered positive when 10% of tumor cells showed immunoreactivity. GS was considered positive when 50% of tumor cells showed immunoreactivity. Results:GPC-3 was positive in 13 of 30 LG-HCCs and 0 of 18 adenomas. The sensitivity was 43% and the specificity was 100%. HSP-70 was positive in 14 of 30 LG-HCCs and 0 of 18 adenomas. The sensitivity was 46% and the specificity was 100%. GS was positive in 24 of 30 LG-HCCs and 9 of 18 adenomas. The sensitivity was 80% and the specificity was 50%. Conclusions:GPC-3 and HSP-70 are helpful in separating carcinomas from adenomas. GS is not useful in this clinical context.

PAX8 and PAX2 immunostaining facilitates the diagnosis of primary epithelial neoplasms of the male genital tract

PAX8 and PAX2 are cell-lineage-specific transcription factors that are essential for the development of Wolffian and Müllerian ducts and have recently emerged as specific diagnostic markers for tumors of renal or Müllerian origin. Little is known about their expression in the Wolffian duct-derived human male genital tract. We report our findings of PAX8 and PAX2 expression in the epithelium of the normal male genital tract and in epithelial tumors derived therefrom using immunohistochemistry (IHC). We found that PAX8 and PAX2 were expressed in the epithelium of the male genital tract from the rete testis to the ejaculatory duct. Rare glands in the prostatic central zone, a tissue of purported Wolffian duct origin, were focally positive for PAX2, but no PAX8 was detected in this area, a finding that may warrant further study. We found diffuse expression of PAX8 and PAX2 in 1 case each of serous cystadenoma of the epididymis, carcinoma of the rete testis, Wolffian adnexal tumor of the seminal vesicle, and endometrioid carcinoma of the seminal vesicle. Neither PAX8 nor PAX2 was detected in the seminiferous tubules and interstitium of the normal testis, nor in Leydig cell tumors (n=6), Sertoli cell tumors (n=2), or 48 of 49 germ cell tumors. One pediatric yolk sac tumor showed focal and weak staining for PAX8. Tumors of mesothelial origin, that is, adenomatoid tumors (n=3) and peritoneal malignant mesotheliomas (n=37) in men, were negative for PAX2 and PAX8. Neither PAX2 nor PAX8 was present in other areas of the prostate. Expression of PAX8 and PAX2 in these primary epithelial neoplasms of the male genital tract is due to their histogenetic relationship with Wolffian or Müllerian ducts. PAX8 and PAX2 IHC may facilitate the diagnosis of these tumors and should be included in the differential diagnostic IHC panel.

Hepatic Granulomas: Pathogenesis and Differential Diagnosis

Granulomatous liver disease constitutes a category of hepatic disorders and is at present diagnosed in approximately 4% of liver biopsies. Hepatic granulomas develop through the interactions of T lymphocytes and macrophages, with the integral involvement of T-helper (T(H)) 1 or T(H)2 pathways or both, depending on the specific granulomatous disease. Hepatic granulomas may be manifested clinically by elevated levels of serum alkaline phosphatase and g-glutamyltransferase enzymes, damage to specific structures (eg, intrahepatic bile ducts in primary biliary cirrhosis), or infrequently, progressive liver disease with portal hypertension and cirrhosis (eg, sarcoidosis). Systemic immunologic disorders, infectious diseases, drug hepatotoxicity, and reaction to neoplastic disease are the major causative factors responsible for granulomas in the liver. These causes and recent epidemiologic trends are covered in this discussion.

Cardiac sarcoidosis: a pathology-focused review.

CONTEXT Sarcoidosis is a granulomatous disease of unclear etiology. It is not commonly fatal, but when sarcoidosis is fatal, it is most often from cardiac involvement and when sarcoidosis involves the heart, it frequently causes death. The disease presents diagnostic challenges both clinically and histologically. OBJECTIVES To review the histology of cardiac sarcoidosis and the histologic differential diagnosis of cardiac granulomatous disease and to review the epidemiology and gross pathology of cardiac sarcoid as well as discuss current controversies, clinical diagnostic criteria, and proposed mechanisms of pathogenesis. DATA SOURCES We reviewed the literature searchable on PubMed as well as selected older studies revealed by our review of the recent literature. Photographs were taken from cases on file at the University of Pittsburgh Medical Center (Pittsburgh, Pennsylvania) and Columbia University Medical Center (New York, New York). CONCLUSIONS Sarcoidosis is a focal or disseminated granulomatous disease that likely represents the final common pathway of various pathogenic insults in a genetically susceptible host. The type of insult may influence the specific sarcoid phenotype. Controversy still abounds, but many areas of investigation around sarcoidosis are yielding exciting discoveries and bringing us closer to a richer understanding of this puzzling disease.

Utility of Glucose Transporter 1 in the Distinction of Benign and Malignant Thoracic and Abdominal Mesothelial Lesions

CONTEXT Malignant mesothelioma, of either peritoneum or pleura, is an uncommon cancer. The diagnosis is often difficult to make, in part because of the overlapping morphology of reactive and malignant mesothelial cells. Glucose transporter 1 (GLUT-1) is a glucose transporter typically found on erythrocytes, which is aberrantly expressed in various carcinomas. It has recently been reported as specific and sensitive in discriminating malignant pleural mesothelioma from reactive hyperplasia. The application of GLUT-1 staining in peritoneal mesothelioma has not been fully explored. OBJECTIVE To determine if GLUT-1 staining is helpful in distinguishing abdominal mesotheliomas from benign, reactive mesothelial lesions and to further study its utility in the thorax. DESIGN Tissue microarrays containing 135 abdominal malignant mesotheliomas and 30 malignant pleural mesotheliomas were stained with an antibody to GLUT-1, as were 56 reactive mesothelial lesions. RESULTS The overall sensitivity and specificity for GLUT-1 in mesothelioma was 53% and 98%, respectively. The sensitivity in epithelioid malignant mesothelioma was 49% and in sarcomatoid/biphasic malignant mesothelioma, 66%. In the thorax, the sensitivity was 50% and in the abdomen it was 54%. The positive predictive value of GLUT-1 immunoreactivity was 98% and the negative predictive value was 40%. CONCLUSION Glucose transporter 1 staining of thoracic mesotheliomas showed high specificity but lower sensitivity than previously reported. Abdominal malignant mesotheliomas showed similar results. Because of low sensitivity, only positive staining is informative. In both sites, the utility of the stain was limited by nonspecific staining (eg, in necrotic areas) as well as bright labeling of erythrocytes and occasional lymphoid elements. Despite these limitations, GLUT-1 can help differentiate malignant mesothelioma from reactive benign mesothelium.

Olmesartan-associated sprue-like enteropathy: a systematic review with emphasis on histopathology

Sprue-like enteropathy associated with the angiotensin II receptor blocker (ARB) olmesartan was first described in 2012, and a number of cases have since been reported. This syndrome is characterized by severe diarrhea and sprue-like histopathologic findings in the intestine, often with increased subepithelial collagen. The incidence of this adverse drug reaction is not entirely clear, although it is thought to be rare. It is also not well established if other ARBs cause such a syndrome, although case reports suggest they can. The histopathologic features of olmesartan-related injury have only been described in a limited number of cases, and there are no guidelines regarding the histopathologic distinction of olmesartan-associated enteropathy from other causes of sprue (eg, celiac disease, tropical sprue). Herein, we review the histopathologic changes and clinical observations described in recent reports of olmesartan-associated sprue-like enteropathy comprising case series and isolated reports, other relevant literature, and our experience at a referral center specializing in small intestinal disorders. We will review recent literature suggesting other ARBs can be associated with a similar phenotype. Lastly, we will discuss the histopathologic differential diagnosis and provide clues to distinguish this entity from other entities which can cause sprue-like histopathology.

Sprue-like histology in patients with abdominal pain taking olmesartan compared with other angiotensin receptor blockers

Aims A severe syndrome characterised by life-threatening diarrhoea and severe sprue-like histology has been described in patients taking the angiotensin receptor blocker (ARB) olmesartan. It is unknown whether there are any histopathological changes in patients without severe diarrhoea exposed to this medication. It is also unknown whether other ARBs cause sprue-like histology. Methods Retrospective cohort study of patients with abdominal pain undergoing upper gastrointestinal endoscopy with duodenal biopsy who were taking ARBs. Patients taking olmesartan (n=20) and a non-olmesartan ARB (n=20) were compared with age and sex-matched controls. Histological features (classic sprue-like and other inflammatory changes) were analysed. Results No single histopathological finding was significantly more common in olmesartan-using patients than controls. However, 10 of 20 olmesartan patients had one or more sprue-like histological features compared with 4 of 20 age-matched and sex-matched controls not taking ARBs (p=0.10). Patients taking ARBs other than olmesartan were not more likely than controls to have one or more of these sprue-like histological features (9/20 vs. 12/20, p=0.34). Conclusions There were no statistically significant differences between olmesartan users with abdominal pain and controls for any single histopathological abnormality. However, there were trends towards significance for individual abnormalities as well as for a composite outcome of sprue-like changes. This raises the possibility that there is a spectrum of histological changes associated with olmesartan use.

Bile salt export pump: a sensitive and specific immunohistochemical marker of hepatocellular carcinoma.

Bile salt export pump (BSEP) is a transporter expressed exclusively at hepatic canaliculi and drives bile‐salt efflux. Minimal data exist about BSEP expression in tumours. We hypothesized that BSEP immunohistochemistry would be specific for hepatocellular carcinoma (HCC).