College of American Pathologists
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September 2002

Sertoli cell tumor of the testis mimicking seminoma
Distinguishing Sertoli cell tumors from seminoma is critical to ensure proper treatment. The authors described 13 cases of Sertoli cell tumor that mimicked seminoma. All of the cases were received in consultation and most were mistakenly diagnosed as seminoma by the referring pathologist. The tumors were confused with seminoma because of their nested pattern of growth, prominence of clear cells, lymphoid infiltrate, inconspicuous tubular differentiation, cytoplasmic glycogen, and prominent nucleoli. Features that help distinguish Sertoli cell tumors from seminoma include smaller, less pleomorphic nuclei, lower mitotic rate, absence of intratubular germ cell neoplasia, absence of granulomatous inflammation, and presence of plasma cells and eosinophils in some cases. Additional clinical features worth noting include recurrent tumor at a site treated by radiation therapy and age greater than 55 years. Immunohistochemical stains that are helpful if seminoma is in the differential based on morphologic examination include inhibin-a, epithelial membrane antigen, cytokeratin, and placental alkaline phosphatase. The first two are positive in Sertoli cell tumor and not in seminoma. Cytokeratin may be weak and focally expressed in seminoma, however, stronger reactivity is seen in Sertoli cell tumor when present. Placental alkaline phosphatase is negative in Sertoli cell tumor and positive in most seminomas.

Henley JD, Young RH, Ulbright TM. Malignant Sertoli cell tumors of the testis: a study of 13 examples of a neoplasm frequently misinterpreted as seminoma. Am J Surg Pathol. 2002; 26:541-550.

Reprints: Dr. J.D. Henley, Dept. of Surgical Pathology, University Hospital 3465, 550 N. University Blvd., Indianapolis, IN 46202-5280

Excisional biopsy for lobular carcinoma in situseen on needle core biopsy
Percutaneous image-guided core biopsy is becoming the method of choice to evaluate impalpable breast lesions presenting with mammographically detected calcifications or as a mammographically detected mass. A diagnosis of a primary lobular lesion is seldom rendered by needle core biopsy. Although lobular carcinoma in situ and atypical lobular hyperplasia are not detected by mammography, they can be associated with calcifications. It is difficult to manage patients with a primary diagnosis of LCIS or ALH on needle core biopsy. Treatment recommendations include excisional biopsy, tamoxifen citrate therapy, mammographic surveillance, or a combination of these approaches. The authors conducted a study on the histologic findings of excisional biopsies performed after ALH or LCIS was found in a needle core biopsy. Hematoxylin and eosin-stained slides of 20 needle core biopsy specimens from patients with a primary diagnosis of LCIS or ALH were retrieved from the consultation and surgical pathology files of New York Presbyterian Hospital-Weill Medical College of Cornell University. Histologic diagnoses were confirmed in all cases. Fourteen cases of primary LCIS and six cases of ALH found on needle core biopsy were identified. Subsequent excisional biopsy of the 14 LCIS cases revealed: LCIS, ductal carcinoma in situ, invasive carcinoma (one patient; seven percent); LCIS, infiltrating lobular carcinoma (one patient; seven percent); LCIS, ductal carcinoma in situ (one patient; seven percent); LCIS (eight patients; 57 percent); and ALH with or without atypical ductal hyperplasia (three patients; 21 percent). Of the six patients with ALH on needle core biopsy, one had infiltrating lobular carcinoma and LCIS and two had LCIS in subsequent excisions. Other excisions for ALH were benign. Three (21 percent) of 14 patients with a primary diagnosis of LCIS on needle core biopsy had a more significant lesion (ductal carcinoma in situ or invasive carcinoma) in a subsequent excisional biopsy. The authors concluded that excisional biosy may be indicated and should be considered when LCIS is found on needle core biopsy in order to more fully examine the biopsy site for coexistent, clinically inapparent intraductal or invasive carcinoma that may be present in about 25 percent of these patients. Although the small number of ALH cases studied produced inconclusive results, the authors recommended that excisional biopsy be considered if atypical ductal hyperplasia is present with ALH in a needle core biopsy or if the diagnosis of the biopsy specimen is discordant with the mammographic findings.

Shin SJ, Rosen PP. Excisional biopsy should be performed if lobular carcinoma in situ is seen on needle core biopsy. Arch Pathol Lab Med. 2002;126:697-701.

Reprints: Dr. Sandra J. Shin, Dept. of Pathology, Starr 1028, New York Presbyterian Hospital-Weill Medical College of Cornell University, 525 E. 68th St., New York, NY 10021;

Quality assurance in immunohistochemistry
The practicability of quality assurance in immunohistochemistry and its integration into the diagnostic process were tested in a large interlaboratory trial in Germany. One hundred and seventy-two pathologists received one hematoxylin and eosin-stained slide and five unstained slides from five cases. All cases were selected by a panel because immunohistochemistry was required for final diagnosis. Participants rendered a morphologic diagnosis and then substantiated it immunohistochemically. The panel reviewed stained slides and evaluation sheets and analyzed the diagnostic process in individual steps: morphologic diagnosis, selection of antibodies, staining quality, interpretation of stained slides, conclusions, and final diagnosis. Diagnosis-independent immunohistochemical performance was tested using a multisample tissue block (30 samples) that was stained and evaluated for six common antigens. For individual cases, corresponding to their difficulty, 21 to 89 percent of the final diagnoses (57 percent from 828 diagnoses) were correct. In a statistical analysis, the independent factors in reaching the diagnosis were the tentative diagnosis, interpretation of stains, and conclusions drawn from immunohistochemistry. Sensitivity to detect estrogen receptors on the multisample tissue block was only 48 percent. Twenty-four percent of the stains, however, were interpreted as falsely negative. The low staining sensitivity did not correlate with the number of correct diagnoses. The major problem of applying immunohistochemistry in surgical pathology appears to be integrating it into the diagnostic process and not the staining quality. Future quality control projects and training will have to take into account these integrative requirements. Multisample tissue blocks provide a promising tool to standardize quantitative immunohistochemical parameters, such as receptor or proliferation scores.

Rüdiger T, Höfler H, Kreipe HH, et al. Quality assurance in immunohistochemistry: results of an interlaboratory trial involving 172 pathologists. Am J Surg Pathol. 2002;26(7):873-882.

Reprints: Dr. Thomas Rüdiger, Institute of Pathology, University of W├╝rzburg, Josef-Schneider-Strasse 2, D-97080, Würzburg, Germany;