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  Anatomic Abstracts

 

 

 

 

January 2012

Editors:
Michael Cibull, MD
Thomas Cibull, MD
Rouzan Karabakhtsian, MD

Interface membrane specimens for the histological diagnosis of prosthetic joint infection Interface membrane specimens for the histological diagnosis of prosthetic joint infection

The authors conducted a study to identify the most accurate specimen for the histological diagnosis of prosthetic joint infections (pseudocapsule or interface membrane). The prospective study included hip revision arthroplasties performed from January 2007 to June 2009. The authors obtained specimens from pseudocapsule and interface membrane from each patient. The histology was considered positive for infection when five or more neutrophils per high-power field (×40) were found. A definitive diagnosis of infection was considered when two or more cultures were positive for the same microorganism. According to the definition of infection, patients were classified in two groups: patients with aseptic loosening in whom cultures obtained during surgery were negative, and patients with prosthetic joint infection. The study involved 69 revisions: 57 were classified as group A and 12 as group B. In group B, the percentage of positive interface membrane histology was significantly higher than the percentage of positive pseudocapsule histology (83 percent versus 42 percent; P=0.04, Fisher’s exact test). The results suggest that periprosthetic interface membrane is the best specimen for the histological diagnosis of prosthetic joint infection.

Bori G, Muñoz-Mahamud E, Garcia S, et al. Interface membrane is the best sample for histological study to diagnose prosthetic joint infection. Mod Pathol. 2011;24(4):579–584.

Correspondence: Dr. G. Bori at gbori@clinic.ub.es
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Effect of prolonged fixation on evaluation of ER, PR, and HER2 expression in breast cancer Effect of prolonged fixation on evaluation of ER, PR, and HER2 expression in breast cancer

Expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 is important in predicting a response to targeted therapies in breast cancer. Therefore, immunohistochemical assays to determine hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status must be accurate and reproducible. Tissue fixation has been shown to play a crucial role in determining consistency in quality. Although guidelines impose upper limits for the fixation period, the data on which these limits are based are scant. The authors conducted a study to prospectively examine the effect of fixation of longer than 72 hours on these assays. In 101 invasive breast cancer samples, HR and HER2 status were compared between tumor blocks undergoing a short fixation period and those undergoing a period of prolonged fixation. Discordances were classified as an incremental change between categories of (i) a single order of magnitude—that is, a difference in the status of low positive (Allred score, 3) compared with positive (Allred score, 4 to 8) or negative (Allred score, 0 or 2) and vice versa for HRs and a difference in HER2 status of equivocal compared with negative or positive and vice versa or (ii) greater than a single order of magnitude—that is, a difference in the status of positive compared with negative or vice versa. The median fixation time for the short fixation group was 13 hours and 18 minutes (mean, 13 hours and 17 minutes; range, 10 hours and 33 minutes to 17 hours and 45 minutes) and for the prolonged fixation group was 79 hours and 22 minutes (mean, 79 hours and 35 minutes; range, 73 hours and 33 minutes to 102 hours and 30 minutes). Eight cases showed discordances, all of which were of a single order of magnitude, including one for ER, five for PR, and two for HER2. In six of these, a higher score was seen in the prolonged fixation group. The authors concluded that fixation for limited periods beyond 72 hours does not reduce assay sensitivity in determining ER, PR, or HER2 immunohistochemical status.

Tong LC, Nelson N, Tsourigiannis J, et al. The effect of prolonged fixation on the immunohistochemical evaluation of estrogen receptor, progesterone receptor, and HER2 expression in invasive breast cancer: a prospective study. Am J Surg Pathol. 2011;35:545–552.

Correspondence: Anna Marie Mulligan at mulligana@smh.ca
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Assessment of low-grade mucinous adenocarcinoma of the uterine corpus Assessment of low-grade mucinous adenocarcinoma of the uterine corpus

Uterine corpus mucinous epithelial proliferations present diagnostic challenges because they are similar histologically to cervical lesions. The authors presented a rare but distinctive endocervical-like mucinous carcinoma of the uterine corpus resembling adenoma malignum of the cervix that can be mistaken for a benign endometrial process. They evaluated the clinical-pathologic features of 16 endometrial carcinomas exhibiting a pure endocervical-like mucinous proliferation. They assessed hysterectomy and available prehysterectomy specimens for architectural complexity, nuclear pleomorphism, macronucleoli, nuclear pseudostratification, mitotic index, necrosis, prominent neutrophils, and voluminous extracellular mucin (mucin encompassing more than 50 percent of a × 40 field). Cases involving the cervix or lower uterine segment were confirmed as endometrial in origin based on immunohistochemical stains (estrogen receptor, progesterone receptor, p16, and vimentin). Patient age ranged from 45 to 70 years. Six of 16 cases (38 percent) were premenopausal; 11 of 16 (69 percent) had abnormal bleeding; and seven of 16 (44 percent) had a history of hormonal therapy. Prehysterectomy diagnoses were benign in two of 16 cases (13 percent), borderline in nine of 16 cases (56 percent), and carcinoma in five of 16 cases (31 percent), whereas eight of 16 hysterectomy specimens (50 percent) showed myoinvasive adenocarcinoma. With the exception of two cases, architectural complexity was low to moderate, and no specimens showed marked nuclear pleomorphism. Macronucleoli and abundant mitotic activity were absent. Nuclear pseudostratification was present in seven of 16 cases (44 percent), necrosis in one of 16 cases (six percent), prominent neutrophils in seven of 16 cases (44 percent), and voluminous extracellular mucin in nine of 16 cases (56 percent). The authors concluded that cytologically bland mucinous epithelial proliferations should be diagnosed with caution in endometrial samplings. The presence of an endocervical-like mucinous epithelial process in association with voluminous extracellular mucin should prompt consideration for a low-grade mucinous adenocarcinoma of the uterine corpus.

Fujiwara M, Longacre TA. Low-grade mucinous adenocarcinoma of the uterine corpus: a rare and deceptively bland form of endometrial carcinoma. Am J Surg Pathol. 2011;35(4):537–544.

Correspondence: Dr. Mika Fujiwara at mfuji war@stanford.edu
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Error rates in reporting prostatic core biopsies Error rates in reporting prostatic core biopsies

The authors conducted a study to evaluate the false-negative and false-positive error rates in a screening and nonscreening population. A total of 4,192 prostatic biopsies were reported in a six-year period by 15 consultant histopathologists, two of whom had an interest in uropathology and were deemed to be specialists. The histopathologists reviewed all biopsies prior to a multidisciplinary team meeting. The overall false-negative rate was 1.7 percent (screening, 2.1 percent; nonscreening, 1.5 percent). The overall false-positive rate was 0.5 percent (screening, 0.9 percent; nonscreening, 0.4 percent). These error rates varied among pathologists, with the false-negative rate ranging from zero to 9.3 percent and the false-positive rate ranging from zero to 3.8 percent. The authors determined that the false-negative rate was three times greater than the false-positive rate, showing that detection of significant pathology is far greater in the negative biopsies. More errors occurred in the screening population than in the nonscreening population. The consultants making the most errors were nonspecialists, but the specialists also made false-negative errors, suggesting that using specialist reporting alone would not have eradicated errors.

Oxley JD, Sen C. Error rates in reporting prostatic core biopsies. Histopathology. 2011;58 (5):759–765.

Correspondence: Dr. J. Oxley at jon.oxley@nbt.nhs.uk
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Perineural invasion in pT3N0 rectal cancer: the incidence and its prognostic effect Perineural invasion in pT3N0 rectal cancer: the incidence and its prognostic effect

The authors conducted a study to explore the incidence and prognostic significance of perineural invasion in pT3N0 rectal cancer. They retrospectively collected pathologic materials from the resected specimens of 173 patients with pT3N0 rectal cancer. They categorized perineural invasion (PNI) positivity into two groups: surrounding the nerve sheath (SS-PNI) and invading through the nerve sheath (TS-PNI). The authors compared the rate of PNI positivity with PNI as initially recorded in the original reports. Patient outcome was studied in groups with different PNI statuses, and multivariate analysis was performed to determine its prognostic value. In this retrospective analysis, the authors found PNI positivity related to lymphovascular invasion in 24.3 percent of all cases—11 percent for SS-PNI and 13.3 percent for TS-PNI. Only 7.5 percent of patient specimens were reported as PNI positive in the original reports. The authors indicated that it was more difficult to detect SS-PNI than TS-PNI. The rates of local recurrence, disease-free survival, and overall survival at five years were similar between the two groups. The five-year local recurrence rate was more than 2.5-fold higher in the PNI-positive group compared with the PNI-negative group (22.7 percent versus 7.9 percent, respectively; P=0.017). Multivariate analysis proved that PNI positivity was the only independent risk factor for predicting five-year local recurrence rate, whereas only sampled lymph nodes were related to five-year disease-free survival and overall survival. The authors concluded that PNI is a common pathologic feature in rectal cancer. The definition of PNI should include SS-PNI and TS-PNI. Rectal cancer patients who are PNI positive are at higher risk of local recurrence and should be considered for more intensive treatment.

Peng J, Sheng W, Huang D, et al. Perineural invasion in pT3N0 rectal cancer: the incidence and its prognostic effect. Cancer. 2011;117:1415–1421.

Correspondence: Dr. Sanjun Cai at caisanjun@gmail.com
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Anatomic pathology abstracts editors: Michael Cibull, MD, professor and vice chair, Department of Pathology and Laboratory Medicine, University of Kentucky College of Medicine, Lexington; Rouzan Karabakhtsian, MD, assistant professor of pathology and laboratory medicine, University of Kentucky College of Medicine; and Thomas Cibull, MD, dermatopathologist, Evanston Hospital, NorthShore University HealthSystem, Evanston, Ill.