Anatomic pathology selected abstracts

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Editors: Rouzan Karabakhtsian, MD, PhD, professor of pathology and director of the Women’s Health Pathology Fellowship, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY; Shaomin Hu, MD, PhD, staff pathologist, Cleveland Clinic; S. Emily Bachert, MD, breast pathology fellow, Brigham and Women’s Hospital, Boston; and Amarpreet Bhalla, MD, assistant professor of pathology, Albert Einstein College of Medicine, Montefiore Medical Center.

Pathologic abnormalities in biopsy samples from the appendiceal orifice

June 2022—Appendiceal orifice mucosae often appear inflamed endoscopically, even when other colonic segments appear normal. Histological findings in biopsy samples taken from endoscopically abnormal mucosae may simulate a variety of inflammatory colitides. The authors performed a double-cohort study to evaluate the clinical implications of inflammatory changes isolated to the appendiceal orifice. They reviewed biopsy samples from 26 histologically abnormal appendiceal orifices. Twenty-five control cases were culled from endoscopically normal-appearing (n=11) and abnormal (n=14) appendiceal orifices, all of which revealed normal histology. Histological findings were correlated with presentation, medication history, findings at other colonic sites, and clinical outcomes. Study cases displayed active inflammation (n=12), chronic active inflammation (n=13), or features simulating collagenous colitis (n=1). Eighteen patients had biopsies taken from other colonic sites that revealed benign polyps (n=10) or displayed active (n=4) or chronic active (n=4) inflammation. All patients with findings isolated to the appendiceal orifice were asymptomatic at their most recent clinical follow-up. Four of eight of the patients with inflammation in other biopsy samples were ultimately diagnosed with ulcerative colitis, in keeping with the well-established role of the appendix as a skip lesion in that disorder. Control patients presented for screening colonoscopy (n=19), iron deficiency anemia (n=3), or change in bowel habits (n=3). None reported gastrointestinal symptoms on follow-up, regardless of the endoscopic appearance of the appendiceal orifice. The authors concluded that isolated inflammation of appendiceal orifice mucosae should not be regarded as a feature of evolving inflammatory bowel disease or other types of chronic colitis.

Castrodad-Rodrıguez CA, Choudhuri J, El-Jabbour T, et al. Clinical significance of pathologic abnormalities in biopsy samples from the appendiceal orifice. Histopathology. 2021;79:751–757.

Correspondence: Dr. Nicole C. Panarelli at npanarel@montefiore.org

Discordance between transient elastography and liver biopsy in evaluations for fibrosis and steatosis

Vibration-controlled transient elastography (VCTE) is a noninvasive method for evaluating liver fibrosis and steatosis. It easily can be performed in the outpatient setting and has been suggested as an alternative to liver biopsy. However, discrepancies between VCTE and biopsy commonly occur. Patient characteristics, procedure performance, and liver features can impact the reliability of VCTE results. The authors identified 82 patients who received VCTE and biopsy within one month of each other to elucidate the clinical scenarios that may require both VCTE and liver biopsy. In the study, 29 (35.4 percent) patients had a major fibrosis discrepancy, which was defined as a finding of advanced fibrosis or cirrhosis by VCTE and minimal or no fibrosis on biopsy. Discordance in the fibrosis reading was significantly associated with increased body mass index. Liver features that disrupt the liver matrix, including steatohepatitis, inflammation, congestion, and cholestasis, have been found to contribute to discrepancies. Advanced fibrosis or cirrhosis on liver biopsy was detected by VCTE in all patients (n=28). However, VCTE was less sensitive for detecting steatosis, as it missed the diagnosis in 19 percent (four of 21) of patients with moderate to severe steatosis on biopsy. While liver biopsy traditionally has been used for diagnosis, the emergence of noninvasive tools to evaluate for liver fibrosis and steatosis has led to the use of biopsies to confirm findings from noninvasive procedures. VCTE is a highly sensitive tool for detecting liver fibrosis, but it is not as specific as biopsy. Therefore, liver biopsy remains the gold standard for confirming liver fibrosis.

Fang JM, Cheng J, Chang MF, et al. Transient elastography versus liver biopsy: discordance in evaluations for fibrosis and steatosis from a pathology standpoint. Mod Pathol. 2021;34(10):1955–1962.

Correspondence: Dr. J. M. Fang at fjiayun@med.umich.edu

Standardizing the reporting of pancreatoduodenectomy specimens for PDAC

Recent literature and international meetings have shown that there are significant differences regarding the definition of what constitutes margins and how best to document the pathologic findings in pancreatic ductal adenocarcinoma. To capture the current practice, the Pancreatobiliary Pathology Society grossing working group conducted an international multispecialty survey encompassing 25 statements regarding the pathologic examination and reporting of pancreatic ductal adenocarcinoma, particularly in pancreatoduodenectomy specimens. The survey results highlighted several discordances. However, pathologists and surgeons reached a consensus or high concordance on the following statements. The pancreatic neck margin should be submitted en face and if any tumor is present on the slide, it should be considered equivalent to R1 resection. The uncinate margin should be submitted in its entirety and perpendicularly sectioned, and the distance of the tumor from the uncinate margin should be reported. Surfaces such as the vascular groove, posterior surface, and anterior surface should be examined and documented. Carcinoma in celiac axis specimens submitted separately should be staged as pT4. Although the participants did not reach a consensus regarding what constitutes R1 versus R0 resection, most agreed that ink on the tumor or no more than 1 mm from the tumor is equivalent to R1 only in areas designated as a margin, not a surface. The authors concluded that this survey serves as a starting point for further standardizing pancreatoduodenectomy grossing and reporting protocols.

Dhall D, Shi J, Allende DS, et al. Towards a more standardized approach to pathologic reporting of pancreatoduodenectomy specimens for pancreatic ductal adenocarcinoma: cross-continental and cross-specialty survey from the Pancreatobiliary Pathology Society Grossing Working Group. Am J Surg Pathol. 2021;45:1364–1373.

Correspondence: Dr. Grace E. Kim at grace.kim@ucsf.edu

Clinicopathologic study of CD34-negative solitary fibrous tumor

CD34-negative solitary fibrous tumors are rare and have not been studied comprehensively. The authors retrospectively reviewed all cases of solitary fibrous tumor (SFT) confirmed with STAT6 IHC or STAT6 gene fusion between 2013 and 2020 and collected pertinent clinicopathologic information. Of 244 cases, 25 (10 percent) lacked CD34 expression by IHC. Compared with CD34-positive SFTs, CD34-negative SFTs were more likely to arise in the head and neck area (32 percent CD34-negative versus 24 percent CD34-positive) and present as metastatic disease (28 percent CD34-negative versus one percent CD34-positive). Forty-eight percent of CD34-negative SFTs versus 22 percent of CD34-positive SFTs exhibited high-grade cytologic atypia, such as hypercellularity, round cell or anaplastic morphology, or nuclear pleomorphism. There were no significant differences in the distributions of age, gender, tumor size, mitotic count, tumor necrosis, or risk stratification between CD34-negative and CD34-positive SFTs. In addition, only 56 percent of CD34-negative SFTs displayed a typical hemangiopericytoma-like vascular pattern. Special histologic features among CD34-negative SFTs included prominent alternating hypercellular or fibrous and hypocellular myxoid areas with curvilinear vessels mimicking low-grade fibromyxoid sarcoma, pulmonary edema-like microcystic changes, and prominent amianthoid collagen fibers. The authors concluded that compared with their CD34-positive counterparts, CD34-negative SFTs are more likely to present as metastatic disease, show high-grade nuclear atypia, and lack the characteristic hemangiopericytoma-like vasculature, posing a unique diagnostic challenge. It may be prudent to use STAT6 IHC or molecular studies, or both, in soft tissue tumors that appear CD34-negative and lack conventional SFT histopathologic characteristics.