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Primary melanoma: pitfalls in diagnostic biopsy techniques and interpretations.

A group of 235 patients with melanoma were followed for 10 years. In 25 of these patients, the initial biopsy specimen obtained by the shave, punch, or incisional technique was insufficient to determine the microscopic extent of the lesion. Guidelines for treatment of these patients include evaluation of the deepest level of tumor invasion, a clinical history of the lesion, and a careful physical examination. If any visible melanoma remains, total excisional rebiopsy should be performed before definitive treatment is begun. Of the 25 patients thus managed, recurrences developed in 3 within 2 years of initial treatment. In two patients, reexcisional surgery was carried out, and they are currently free of disease. One patient died from systemic metastases. Total excisional biopsy of lesions suspected of being melanomas is strongly recommended, and shave, punch, or incisional techniques should be avoided.

Adult↗

S-100 protein positivity in breast carcinomas: a potential pitfall in diagnostic immunohistochemistry.

S-100 protein, originally isolated from neural tissues, has also been identified in various normal and neoplastic cells, including malignant melanomas. A systematic immunohistochemical investigation of this antigen was performed on formalin-fixed paraffin-embedded samples of benign and malignant breast tissues with use of the avidin-biotin-peroxidase complex immunoperoxidase technique and a polyclonal antiserum that recognizes both the alpha and beta subunits of S-100 protein. In benign breast tissue, S-100 protein was present in both epithelial and myoepithelial cells of terminal ducts and lobules; the staining was cytoplasmic and sometimes nuclear. Of 100 randomly selected invasive breast carcinomas, 48 per cent contained S-100 protein-positive tumor cells. Lobular and medullary carcinomas (60 per cent and 80 per cent, respectively) were more frequently positive than ductal carcinomas (45 per cent). Dendritic cells, most likely Langerhans' cells, were present in some carcinomas and were also positive for S-100. There was no relationship of S-100 positivity to histologic differentiation, recurrence interval, or the expression of various tumor markers. The presence of S-100 protein positivity in metastatic breast carcinomas may lead to the erroneous diagnosis of malignant melanoma. Our observations underscore the importance of testing for a broad panel of tumor markers rather than relying on single antigens in evaluating metastatic malignancies of undetermined origin.

Adenocarcinoma, Mucinous↗

Large heterozygous deletion masquerading as homozygous missense mutation: a pitfall in diagnostic mutation analysis.

The clinical use of molecular analyses in recessive disorders relies on the exact characterization of both mutant alleles in the affected patient. This can be problematic when only part of the gene is examined or when relevant DNA alterations are not recognized by standard methods. We present a child in whom phenylketonuria was apparently caused by homozygosity for the mutation E390G in exon 11 of the phenylalanine hydroxylase (PAH) gene. However, the clinical severity of the disease was not quite as mild as expected, the mutation was not identified in the father despite confirmed paternity, and the paternal allele showed a highly unusual pattern of polymorphic markers in the PAH gene. Presence of a large deletion involving exons 9, 10 and 11 of the phenylalanine hydroxylase gene was confirmed by long-range PCR. Diagnostic DNA analyses should include a comprehensive examination of the whole relevant gene in the patient and confirmation of carrier status in both parents.

DNA Mutational Analysis↗

Fecal occult blood testing. Problems, pitfalls, and diagnostic concerns.

The diagnostic approach to the asymptomatic patient who has tested positive for fecal occult blood varies among clinicians. Colonoscopic evaluation is the procedure of choice in initiating the workup of patients 50 years of age and older. In younger patients, examination by sigmoidoscopy and barium enema using air for contrast (double contrast study) may be considered as an alternative to colonoscopy as the initial test. Evaluation of the upper gastrointestinal tract should be considered if a colonic source is not detected. The challenge in diagnostic test selection lies in choosing the most appropriate and cost-effective procedure for detecting disease, especially neoplastic lesions.

Barium Sulfate↗

Inhibin is not an immunohistochemical marker for hepatocellular carcinoma. An example of the potential pitfall in diagnostic immunohistochemistry caused by endogenous biotin.

Inhibin is a heterodimeric glycoprotein originally detected in gonadal tissues. One report described inhibin immunopositivity in 17 of 19 hepatocellular carcinomas (HCCs) and the hepatocytes of the surrounding nonneoplastic parenchyma. The reported immunohistochemical method, which used avidin-biotin complex, did not describe blocking endogenous biotin. Since liver tissue may contain high levels of biotin, endogenous biotin may result in false-positive immunostaining. We wondered whether this reported immunopositivity represented a false-positive result due to unblocked endogenous biotin. By using a similar antigen retrieval technique and the same specificity, titer, and clonal source of primary antibody as the aforementioned study, we performed immunostaining for inhibin with and without an endogenous biotin blocking step on 23 cases of HCC and the surrounding cirrhotic liver. In all cases, the HCC and the hepatocytes in the cirrhotic nodules were negative for inhibin when the endogenous biotin blocking step was used. When the blocking step was omitted, apparent immunostaining was noted in 20 of 23 HCCs and in the hepatocytes in all cases. Accordingly, HCC and the hepatocytes of the surrounding cirrhotic liver are immunohistochemically negative for inhibin. The previously reported immunopositivity of HCC and nontumoral hepatocytes for inhibin represents a false-positive result due to endogenous biotin.

Biomarkers↗

Lobulated schwannoma of the median nerve: pitfalls in diagnostic imaging.

The authors report an unusual case of volar wrist swelling with the appearance of a simple ganglion on magnetic resonance imaging (MRI); however, operative and histologic examination identified the swelling as an ancient schwannoma. Ancient schwannomas mostly present as a solitary tumor. A lobulated tumor in this location has not been described previously. The pathologic findings of these uncommon tumors and the difficulties encountered in accurate preoperative diagnosis are discussed.

Female↗

Potential pitfalls in diagnostic oral pathology: a review for the general surgical pathologist.

Oral developmental, reactive, benign neoplastic and malignant neoplastic conditions, many odontogenic in origin, may not be seen routinely by the general surgical pathologist and therefore may present a diagnostic dilemma. This article describes odontogenic and nonodontogenic conditions with little or no destructive potential along with the more aggressive conditions that resemble them clinically and histologically. The importance of clinical and radiographic correlation as an adjunct to tissue diagnosis is highlighted. Additionally, a brief summary of odontogenesis is presented with attention given to odontogenic embryologic remnants and the developmental and pathologic processes that may arise from them.

Diagnostic Errors↗

Frozen section of skin specimens.

CONTEXT: Skin cancers are the most common malignancies in this country. Treatment of these tumors often involves assessment of margins, which may be performed by frozen section. OBJECTIVE: This article discusses indications for frozen section, various approaches to gross examination of specimens, Mohs micrographic surgery, diagnostic pitfalls, methods to improve diagnostic accuracy, and special techniques. DATA SOURCES: The authors' extensive experience and review of the published literature. CONCLUSIONS: Frozen sections play a vital role in the evaluation of margins of basal cell carcinomas and squamous cell carcinomas. The role of frozen sections in evaluation of soft tissue tumors is controversial. With rare exception, they have no role in the evaluation of melanocytic tumors.

Basal Cell Carcinoma↗

Pitfall in diagnostic trauma laparoscopy.

The resurging interest in diagnostic laparoscopy has witnessed its increasing application in trauma surgery. Such unbridled enthusiasm has at times overlooked its shortcoming in the diagnosis and management of certain in abdominal injuries. We report and discuss one such conspicuous limitation and advocate that the use laparoscopy in abdominal trauma should be tempered with caution.

Abdominal Injuries↗

Malignant peritoneal mesothelioma. Case-report demonstrating pitfalls of diagnostic laparoscopy.

Patients with peritoneal mesothelioma present with abdominal distension and clinical syndrome of debilitating ascites. Cytology of the peritoneal fluid obtained by laparocentesis often does not result in a diagnosis. Laparoscopy with biopsy of peritoneal nodules is a valuable method by which a histological diagnosis is established. However laparoscopy can greatly complicate the management of peritoneal mesothelioma by facilitating tumor dissemination to port sites. The patient presented was treated with cytoreductive surgery and perioperative intraperitoneal chemotherapy. Although palliation of intra-abdominal tumor and ascites was achieved, port sites-disease required extensive resection of the abdominal wall. Our experience with this patient suggests that if a malignant source of ascites is suspected and a diagnosis is not obtained by paracentesis, laparoscopy should be used to establish a diagnosis. However, trocars should only be placed along the midline of the abdominal wall so that port sites can be excised at the time of cytoreductive surgery. This diagnostic strategy is applicable to the majority of patients undergoing laparoscopy when there is known or suspected intraabdominal malignancy.

Ascites↗

Gender differences in detecting coronary artery disease with dipyridamole stress myocardial perfusion imaging using 99m-Tc sestamibi gated SPECT.

There are some specifics in the presentation of coronary artery disease (CAD) in women compared with men that may cause diagnostic pitfalls. The accuracy of noninvasive diagnostic testing in women tends to be lower than that in men. Stress myocardial perfusion imaging with 99m-Tc sestamibi gated SPECT is an accurate technique for detecting CAD. Only a few studies have compared dipyridamole stress imaging according to gender. The aim of the study was to compare the diagnostic value of dipyridamole myocardial perfusion imaging with 99m-Tc sestamibi gated SPECT in detecting CAD among patients of both sexes. We studied 62 consecutive patients (38 men, 24 women) using 99m-Tc sestamibi gated SPECT and dipyridamole stress to detect CAD. All the patients also underwent coronary angiography. Overall regional sensitivity was significantly lower in women compared with men (71.4% vs. 92.7%, p=0.039). There were no significant differences for detecting CAD in individual coronary arteries, although regional sensitivity in all three vascular territories was higher in men compared to women. The lowest sensitivity in women was found in the LAD territory (66.6%). Overall regional specificity in men and women was similar and did not reach statistical significance (88.7% vs. 94.7%). Significantly lower specificity in men was found only in the RCA territory (79.1%), compared with that in women (100%). Our results confirmed that there are certain gender differences in the diagnostic performance of dipyridamole stress myocardial perfusion imaging with 99-Tc sestamibi gated SPECT which are assigned to the characteristics of the female population. However, the diagnostic accuracy is also quite high in women, which makes this technique efficient enough in detecting CAD among this population.

Coronary Angiography↗