College of American Pathologists
Printable Version

  Anatomic Abstracts





cap today

August 2002

False-positive results in fine-needle aspiration biopsy specimens
The authors used data from the CAP Interlaboratory Comparison Program in Nongynecologic Cytopathology to address the rate of interpretation of normal cellular elements as neoplastic (benign and malignant) in fine-needle aspiration biopsy specimens from various body sites. They analyzed diagnoses made between 1998 and 2000. False neoplastic diagnoses were rendered in 60 percent of kidney specimens, 37 percent of liver, 10 percent of pancreas, and six percent of salivary gland. The rates are much higher than previous reports in the literature. The study illustrates that normal cellular elements are a significant pitfall for overinterpretation of fine-needle aspiration biopsy specimens.

Young NA, Mody DR, Davey DD. Misinterpretation of normal cellular elements in fine-needle aspiration biopsy specimens. Arch Pathol Lab Med. 2002;126:670-675.

Reprints: Dr. Nancy A. Young, Dept. of Pathology, Fox Chase Cancer Center, 7701 Burholme Ave., Philadelphia, PA 19111;

Predicting the clinical behavior of gastric stromal tumors
Gastrointestinal stromal tumors are a heterogeneous group of neoplasms that have clinical and histologic features that vary depending on their location within the gastrointestinal tract. It is difficult to predict clinical behavior in this group of tumors, and the same criteria for malignancy do not necessarily apply to stromal tumors from different sites within the gastrointestinal tract. Using known clinical behavior with long-term followup, the authors attempted to determine which features, if any, are associated with clinical behavior in stromal tumors arising in the stomach, the most common site for such tumors. Seventy-seven gastric stromal tumors were studied and classified as adverse outcome (AO) tumors (malignant) or non-adverse outcome tumors (benign) based on their known clinical outcome. Adverse outcome was defined as metastasis or death due to tumor. Patients with a non-AO had at least five years of tumor/metastasis-free followup. Thirty-seven patients had an AO (followup [metastasis at presentation] zero to 73 months; median, six months), and 40 patients had a non-AO (followup, 60 to 264 months; median, 84 months). All cases were reviewed by two of the authors, who were blinded to clinical outcome and gross features. The tumors were classified as histologically benign or not benign using preset, defined histologic criteria based on the authors' prior experience with a large number of these tumors. If the tumor did not fit the characteristic cellular spindle cell or benign epithelioid cell patterns, the tumor was classified as not benign. Clinical outcome was then correlated with the histologic designation to determine if these preset criteria were valid. The authors were able to classify the tumors as benign or not benign with a sensitivity of 100 percent and specificity of 92 percent. For all cases, individual morphologic and clinical features were examined. Features associated with an AO included tumor size of 7 cm or greater, high cellularity, mucosal invasion, high nuclear grade, mitotic counts of at least 5/50 high power fields, mixed cell type, and the presence of a myxoid background or absence of stromal hyalinization. By recognizing several well-defined patterns of benign gastric stromal tumors and the myriad of individual features shown to correlate with an AO, one can better predict the clinical behavior of gastric stromal tumors.

Trupiano JK, Stewart RE, Misick C, et al. Gastric stromal tumors. A clinicopathologic study of 77 cases with correlation of features with nonaggressive and aggressive clinical behaviors. Am J Surg Pathol. 2002;26:705-714.

Reprints: Dr. John R. Goldblum, Cleveland Clinic Foundation, 9500 Euclid Ave., L25, Cleveland, OH 44195;

Endometrial stromal nodules and endometrial stromal tumors with limited infiltration
It is important to recognize the pathologic features of endometrial stromal nodules to avoid confusing them with endometrial stromal sarcoma and other tumors, such as uterine tumor resembling ovarian sex cord tumor. Features that may be seen in endometrial stromal nodules, such as smooth muscle metaplasia, irregular interdigitation of stromal neoplasia with metaplastic smooth muscle, and broad zones of necrosis, may be confused with endometrial stromal sarcoma. The authors emphasize the need for careful gross evaluation and thorough sampling of the margin to avoid this confusion. In three of 50 cases, there were four to six margin irregularities, with some extending from 3 mm to 9 mm beyond the main border of the tumor (endometrial stromal tumor with limited infiltration). These differed from endometrial stromal sarcoma based on the number and pattern of the irregularities noted. Most tumors with margin irregularities had limited followup precluding assessment of prognosis, however, the authors suspect that most such tumors will behave in a benign fashion.

Dionigi A, Oliva E, Clement P, et al. Endometrial stromal nodules and endometrial tumors with limited infiltration: a clinicopathologic study of 50 cases. Am J Surg Pathol. 2002;26:567-581

Reprints: Dr. Esther Oliva, Dept. of Pathology, Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114