The performance of BRCA1 immunohistochemistry for detecting germline, somatic, and epigenetic BRCA1 loss in high-grade serous ovarian cancer.

BACKGROUND: BRCA1 expression can be lost by a variety of mechanisms including germline or somatic mutation and promotor hypermethylation. Given the potential importance of BRCA1 loss as a predictive and prognostic biomarker in high-grade serous ovarian cancer, we sought to evaluate the utility of BRCA1 immunohistochemistry (IHC) in screening for BRCA1 loss by germline, somatic, and epigenetic mechanisms. PATIENTS AND METHODS: Patients with advanced high-grade serous ovarian cancer who had previously undergone germline BRCA1 testing were identified. Samples from each tumor were stained for BRCA1 and reviewed independently by two pathologists blinded to BRCA status. Tumors with abnormal BRCA1 IHC and wild-type germline testing underwent further evaluation for somatic BRCA1 mutations and promoter hypermethylation. McNemar's test was used to determine the association of BRCA1 IHC with germline BRCA1 mutations and BRCA1 loss through any mechanism. Kaplan-Meier methods were used to estimate overall survival (OS), and the log-rank test was used to assess differences between groups. RESULTS: Inter-rater reliability between the two pathologists on BRCA IHC interpretation was very good (kappa coefficient 0.865, P = 0.16; McNemar's test). BRCA1 IHC was abnormal in 36% (48/135) of cases. When compared with germline BRCA1 status, BRCA1 IHC had a high negative predictive value (95.4%) but a low positive predictive value (PPV, 52.1%). When accounting for promoter hypermethylation and somatic mutations as alternative methods of BRCA1 loss, the PPV rose to 87.5%. Five-year OS rate was 49.6% [95% confidence interval (CI) 26.3% to 69.3%] for patients with germline BRCA1 mutations, 50.4% (95% CI 27.5% to 69.5%) for germline wild-type BRCA1 and abnormal IHC, and 52.1% (95% CI 38.4% to 64.2%) for germline wild-type BRCA1 and normal IHC (P = 0.92). CONCLUSIONS: BRCA1 IHC interpretation was a highly reproducible and accurate modality for detecting germline, somatic, or epigenetic mechanisms of BRCA1 loss. These results support further development of BRCA1 IHC as a potential biomarker for BRCA1 loss in high-grade serous ovarian cancer.

Rectal biopsy in the diagnosis of Crohn's disease: value of multiple biopsies and serial sectioning.

We performed a retrospective evaluation of 243 rectal biopsies from 90 patients who eventually had Crohn's disease proven clinically or by surgery. A portion of each rectal biopsy was serially sectioned. Twenty-five of the 90 patients (28%) had epithelioid granulomas. Half of these patients had an epithelioid granuloma in only one of two or more biopsies. Sixteen percent of these granulomas were so small as to be seen in only six or less successive serial 4-microM sections. This high yield of granulomas is probably attributable to the examination of at least 90 serial sections, usually from each of two rectal biopsies per patient. Using partial serial sectioning, epithelioid granulomas were found almost as frequently in grossly normal as in grossly abnormal appearing mucosa. No granulomas were seen in suitable controls including normals and patients with ulcerative colitis or other diseases. When the differential diagnosis between idiopathic ulcerative colitis and Crohn's disease is uncertain, we recommend taking two rectal biopsies and serially sectioning part of each.

Human rectal mucosa: proctoscopic and morphological changes caused by laxatives.

To determine whether laxatives alter the proctoscopic and morphological appearances of the human rectum, 10 normal subjects were studied prospectively, and the following manipulations were assessed in a randomized, blinded manner: no treatment; oral mannitol to induce diarrhea; isotonic saline enema; Fleet's Phospho-Soda enema; and bisacodyl (Dulcolax), 10 mg, by enema or suppository. The rectal mucosa after mannitol-induced diarrhea, or after saline enema could not be distinguished from untreated rectum by proctoscopy, light microscopy, or scanning electron microscopy. Fleet's enema, and bisacodyl invariably changed proctoscopic appearances, and frequently altered light and scanning microscopic aspects. Both Fleet's enema and bisacodyl caused sloughing of surface epithelium. In addition, bisacodyl decreased the uptake of hematoxylin and eosin by crypt epithelial cells so that the affected cells had a partially erased appearance (16 of 25 biopsies examined by light microscopy). The lamina propria of 3 of these 25 biopsies contained polymorphonuclear cells. Transmission electron microscopy revealed that the abnormal crypt epithelial cells contained fewer cytoplasmic organelles and less nuclear chromatin. All lesions resolved within 7 days. Fleet's enema and bisacodyl by rectum may mislead the proctologist and the pathologist by altering normal rectal mucosa.

Overwhelming watery diarrhea associated with a cryptosporidium in an immunosuppressed patient.

A 39-year-old man with severe bullous pemphigoid developed overwhelming diarrhea after 5 weeks' treatment with 150 mg of cyclophosphamide and 60 mg of prednisolone daily. Jejunal and ileal biopsies showed severe mucosal injury and tiny 2- to 4-mu organisms on the epithelial surfaces. Similar organisms were seen in smears of jejunal fluid. Electron microscopic examination of jejunal biopsies showed these spherical bodies to be trophozoites, schizonts, microgametocytes, and macrogametocytes typical of the genus Cryptosporidium. Diarrhea resolved 2 weeks after discontinuation of cyclophosphamide and coincided with disappearance of Cryptosporidia from the jejunal biopsies. Immunosuppression may have predisposed this patient to cryptosporidial diarrhea. Cryptosporidiosis is another infection which can be diagnosed by small bowel biopsy. When immunosuppressed patients develop severe diarrhea, opportunistic infection with this and other organisms should be considered as the possible cause.