Equivocal Diagnosis Research Articles

Cancer of Unknown Primary Site

In the United States, unknown primary cancers represented about 2% of all cancer diagnoses reported between 1973 and 1987.1 Registries from seven other countries have listed incidences from 2.3% to 7.8%.2 These patients are heterogeneous with several clinical presentations and histologic tumor types. Most have metastatic carcinoma of unknown primary site, while others have equivocal pathologic diagnoses with tumors difficult to classify by light microscopic examination. Specialized pathologic studies are essential in diagnosing the type of neoplasm present in many of these patients.

Bilious vomiting in the newborn period: surgical incidence and diagnostic challenges

Aims Bilious vomiting in the newborn is a potentially life threatening emergency. Malrotation, a disorder of abnormal intestinal rotation and fixation, predisposes newborns to midgut volvulus. Plain abdominal films and upper gastrointestinal contrast studies form the mainstay of radiological diagnosis. 1) To determine the incidence of surgical pathology in newborns with bilious vomiting referred to a regional paediatric surgical centre. 2) To assess the predictive value of radiological investigations Methods A total of one hundred and fourteen infants referred for radiological assessment on the day of presentation were identified from the regional radiological database (October 2006–April 2008). Exclusion criteria included abdominal wall defects, congenital cardiac conditions, congenital anomalies and vomiting beyond the neonatal period. A total of 23 infants were excluded. All infants had plain abdominal films and upper gastrointestinal contrast studies. In addition, five infants had abdominal ultrasonography. Results 18.6% (17/91) of newborns presented with intestinal pathology, of which all 17 required surgery. Thirteen newborns (14.2%) had malrotation (seven had additional midgut volvulus), two had a duodenal web, one each had colonic pneumatosis and intussusception. Plain films and clinical examination did not suggest malrotation in the positive cases. Upper gastrointestinal contrast studies diagnosed malrotation in eleven cases, equivocal diagnosis of malrotation in two cases with midline duodenojejunal junction and a diagnosis of duodenal web in a further two cases. The predictive value of upper gastrointestinal contrast studies in diagnosing malrotation was 85%. Ultrasonography secured the diagnosis of midgut volvulus based on the “whirlpool sign”, in the two equivocal cases with midline duodenojejunal junction and this was confirmed during surgery. All thirteen cases had a Ladd9s procedure. None had ischaemic bowel. Conclusion The incidence of malrotation in our population is less than previously reported, probably because our regional policy dictates that all infants with a single bilious vomit require specialist investigation. This study confirms that clinical examination and plain abdominal films have no predictive value in diagnosing midgut volvulus. The study also confirmed that upper gastrointestinal contrast studies, in combination with ultrasound improves the predictive value in diagnosing surgical pathology.

Proliferative Nodules in Congenital Nevi - A Histopathologic, Genetic and Immunohistochemical Reappraisal

Although histopathology is the gold standard for the classification of melanocytic proliferations, in some such as the proliferative nodule, an equivocal diagnosis can be diagnostically extremely challenging based on histopathologic features alone. The purpose of this study was to review the histologic features of proliferative nodules and to ascertain the utility of immunohistochemistry and analyses of oncogenic mutations in signaling components of the MAP kinase pathway as diagnostic adjuncts. Genomic DNA for genotyping was isolated per protocol using techniques that included laser capture microdissection to isolate nevus cells from proliferative nodules (n=3) and age-matched congenital nevi (CN, n=3). Direct DNA sequencing was performed on BRAF codon 600; NRAS1 codons 12 and 13; NRAS2 codons 60 and 61, KRAS codons 12 and 13 and GNAQ. Immunohistochemical analyses were performed using antibodies to nestin, CD133, p53, c-kit and bcl-2. While all 3 cases of proliferative nodules exhibited mitoses, features of concern were not noted in any. Of the genes analyzed, no mutations were identified in any of the PN. Immunohistochemistry revealed the following: nestin in 1 PN (3+) and in 2 CN (both 3+); CD133 negative in all PN and CN; p53 in 1 PN (2+) and 0 in CN; c-kit in 2 PN (2+/3+) and in 3 CN (2+/3+/3+) and bcl-2 in 2 PN (both 3+) and 2 CN (both 3+). Our findings, albeit limited by sample size, suggest that proliferative nodules do not appear to possess a distinctive or unifying genomic signature. In light of evidence indicating that progression to malignant melanoma involves genetic pathways instrumental to stem cell biology, that absence of a sizeable population of stem cells in 2 of 3 of proliferative nodules in the current study supports their putative benign biologic behavior.

A New Generation of Studies of Human Papillomavirus DNA Testing in Cervical Cancer Screening

“All zoogles are boogles. You saw a boogle. Is it a zoogle?” Question in an SAT examination (Nassim Nicholas Taleb in “The Black Swan”) “Not necessarily” is the resounding answer to this thought experiment, in analogy to the central argument in the debate on the clinical utility of human papillomavirus (HPV) testing in cervical cancer screening. Virtually all cervical cancers are caused by infections with oncogenic HPV types ( 1 ). However, does a positive HPV DNA test result indicate that cervical cancer or precancerous lesion is present or imminent for a woman attending routine screening? Although most cervical HPV infections, even those with oncogenic types, will be inconsequential, it is also true that a provider will be more likely to fi nd cervical cancers or their precursors if screening is with HPV DNA testing rather than with Papanicolaou cytology ( 2 , 3 ). This extra sensitivity exacts a penalty on the specifi city of HPV DNA testing, which (by design) detects the presence of viral DNA in cervical cells irrespective of whether or not the molecular changes are in the context of an infection that has already produced morphological abnormalities recognizable by cytology. In other words, HPV DNA testing brings the focus of screening “upstream” in the natural history of cervical neoplasia relative to the decades-old paradigm of Papanicolaou cytology. Returning to the above thought experiment, all cervical cancers arise from cervical intraepithelial neoplasia (CIN), whose grade correlates with the extent of Papanicolaou abnormality. Although it is easier to fi nd a “zoogle” with the HPV DNA “boogle” identifi er than with the Papanicolaou “boogle” identifi er, the latter will have fewer false positives than the former. Recognition of the above-described test properties has not been the main rationale for how the scientifi c community has designed studies to collect evidence on the value of HPV DNA testing in cervical cancer screening and for how professional guidelines emerged in consequence. Although less specifi c than Papanicolaou cytology, the HPV DNA test was fi rst evaluated and approved to be used conditionally as a triage tool based on the Papanicolaou cytology result exclusively to identify women who need to undergo colposcopy because of an equivocal Papanicolaou diagnosis ( 4 , 5 ). Later, mounting evidence that HPV DNA testing could increase the sensitivity of screening when used in parallel with Papanicolaou cytology led to co-testing as an accepted practice that permitted screening intervals in the United States to be safely extended from annual to triennial ( 6 ). The impetus for Papanicolaou and HPV co-testing prompted the initiation of European randomized controlled trials (RCTs) comparing the co-testing strategy with traditional cytology-only screening. The results from these trials have confi rmed that 1) more cervical precancerous lesions are detected by co-testing than by cytology ( 7 – 9 ) and 2) the extra detection is benefi cial because the excisional treatment given at the time of the discovery lowers the rate of such lesions in subsequent screening rounds, thus proving that many of them would likely persist or progress if left untreated ( 8 – 10 ).

Evaluation of immunohistochemistry staining and cytologic diagnosis by using cell block sections prepared with effusion fluid cytology specimens

To study the values of immunohistochemistry staining and cytological diagnosis by using cell block sections prepared with the effusion fluid cytology specimens. Ninety-nine effusion cytology specimens with the diagnoses of reactive mesothelial hyperplasia, atypical cells and metastatic carcinoma were enrolled into the study. The cytospin preparations/smears, cell block sections and immunohistochemical study were performed and correlated with the clinical findings and follow-up data. Amongst the 99 cases studied, the percentage with positive diagnosis using cytospin preparations/smears was 68.7% (68/99). The percentages with negative and equivocal diagnoses were 16.2% (16/99) and 15.1% (15/99), respectively. As for cell block sections, the percentages were 71.7% (71/99), 16.2% (16/99) and 12.1% (12/99), respectively. On the other hands, the percentages became 76.8% (76/99), 20.2% (20/99) and 3.0% (3/99), respectively, when coupled with immunohistochemical findings. The overall percentages of positive, negative and equivocal diagnoses were 77.8% (77/99), 17.2% (17/99) and 5.0% (5/99), respectively, upon clinicopathologic correlation. The difference between cytospin preparations/smears and cell block sections was not statistically significant (P > 0.05). When coupled with immunohistochemical findings or clinicopathologic correlation, the difference in rates of equivocal diagnosis however carried statistical significance (P < 0.05). The false-negative rate of immunohistochemical study applied on cell block sections was 1.0% (1/99). Immunohistochemistry, when applied on cell block sections, is useful in delineation of the primary origins of the tumor cells in effusion fluid cytology specimens. Combination of morphologic examination, immunohistochemical findings and clinicopathologic correlation can further improve the rate of positive diagnosis.

Cytopathological and histopathological diagnosis of canine splenic disorders

To determine (1) the common types of canine splenic disorders, and the breeds affected, that are diagnosed by cytopathological and histopathological examination in Sydney, Australia and (2) the accuracy of cytopathological examination compared with histopathological examination for the diagnosis of canine splenic disorders. 69 cytopathological and 51 histopathological diagnoses of canine splenic disorders presented to the Veterinary Pathology Diagnostic Services, The University of Sydney during 2006 and 2007 were tabulated and analysed; 17 cases examined both cytopathologically and histopathologically during 2001-07 were also analysed. The most common cytopathological diagnoses were benign disorders of growth, vascular disturbances and necrosis (29%), followed by no abnormalities detectable (28%), malignant neoplasms (20%), equivocal diagnoses (20%) and inflammatory disorders (3%). The most common breeds were Kelpie crosses and mixed breeds. The most common histopathological diagnoses were benign disorders of growth, vascular disturbances and necrosis (49%), followed by malignant neoplasms (43%) and inflammatory disorders (8%). The most common breeds were German Shepherd Dogs, Boxers and Maltese Terriers. Cytopathological and histopathological diagnoses were in complete agreement in 59% of cases, partial agreement in 29% and disagreement in 12%. Benign disorders of growth, vascular disturbances and necrosis were the most commonly diagnosed canine splenic disorders, both cytopathologically and histopathologically. Kelpie crosses presented most frequently for cytopathological examination. German Shepherd Dogs were the most common breed diagnosed histopathologically with haemangiosarcoma. Although cytopathological and histopathological splenic examinations are complementary for diagnosis, this study has shown a high correlation for complete and partial agreement between the two.

Biomarker p16INK4a on Paraffin Sections Prepared from Cervical Brush Samples Highlights Nuclear Changes Resulting in Unquestionable Cytohistodiagnosis

To optimize the morphology of pl6-positive atypical and (pre)neoplastic cells in paraffin cytoblock sections with the aim to minimize equivocal diagnoses on cytology samples.Patients with negative cytology results or results within normal limits (WNL) (n=38), atypical squamous cells of undetermined significance (ASCUS) (n=25) and high grade squamous intraepithelial lesion (HSIL) (n=16) were selected. The residual material of the cervical brush samples was processed to cytoblock paraffin sections and stained for pl1. The cytohistodiagnosis of the pl1-stained paraffin sections was based on the cytologic and histologic morphology.Of the 38 cytologically negative cases, only 4 contained afe w faintly positive pl61cells. Of the 25AS CUS cases, I 1as cytohistologically upgraded to low grade squamous intraepithelial lesion (LSIL). All 16 HSIL cases contained cells with outspoken diffuse positive immunostaining, highlighting chromatin clumping in the (pre)malignant cells. In the paraffin sections the tissue fragments showed architecture consistent with that of HSIL. The nuclear to cytoplasmic ratio in the HSIL was severely disturbed.Cervical brush samples allow an unequivocal cytohistodiagnosis based on the (pre)malignant nuclear changes highlighted by the p16 staining of the paraffin sections.

A European consensus for the evaluation and management of infants with an equivocal diagnosis following newborn screening for cystic fibrosis

Screening newborns for cystic fibrosis (CF) is considered to be an ethical undertaking in regions with a significant incidence of the condition. Current screening protocols result in recognition of infants with an equivocal diagnosis. A survey of European practice suggested inconsistencies in the evaluation and management of these infants. We have undertaken a consensus process using a modified Delphi method. This has enabled input of CF specialists from a wide geographical area to a rigorous process that has provided a clear pathway to a consensus statement. A core group produced 21 statements, which were modified over a series of three rounds (including a meeting arranged at the European CF Conference). A final document of 19 statements was produced, all of which achieved a satisfactory level of consensus. The statements cover four themes; sweat testing, further assessments and investigations, review arrangements and database. This consensus document will provide guidance to CF specialists with established screening programmes and those who are in the process of implementing newborn screening in their region.

Diagnostic accuracy of fine‐needle aspiration cytology in histological grade 1 breast carcinomas: are we good enough?

Fine-needle aspiration cytology (FNAC) of both palpable and non-palpable breast carcinomas has a high accuracy and sensitivity in dedicated centres. It is generally thought that low-grade carcinomas have a distinctly lower sensitivity due to discrete cellular atypia that may be difficult to appreciate. Grade 1 carcinomas make up about 45% of screening-detected breast carcinomas and about 20% of symptomatic breast cancers. The aim of this study was to evaluate the diagnostic sensitivity of grade 1 carcinomas and identify the critical features in the cytological diagnostic work-up of these tumours. There were FNAC smears from 494 histologically confirmed grade 1 carcinomas diagnosed during 1996-2004. The cytological diagnoses were compared with the histology. A definitive malignant diagnosis (absolute sensitivity) was given in 382 cases (77.3%). Equivocal or suspicious diagnoses were given in 75 (15.2%), benign or probably benign (false negative) in 24 (4.8%). Thirteen cases (2.6%) were unsatisfactory. Complete sensitivity was 92.7%. Invasive ductal carcinomas comprised 81.3% of all cases; absolute sensitivity for these was 80.9%. Invasive lobular and tubular carcinomas comprised 7.3% and 5.9% of cases, respectively; absolute sensitivity for these diagnosis was 50.0% and 57.1%, respectively, significantly lower than for other subtypes (P <or= 0.0001) whereas the difference for complete sensitivity was less but still significant (P = 0.017). Absolute and complete sensitivities were lower for tumours less than 1 cm size compared with more than 1 cm (P <or= 0.00001). Preoperative FNAC diagnosis of grade 1 breast carcinoma has a high sensitivity, especially in ductal carcinomas. Invasive lobular and tubular carcinomas were less likely to receive a definite preoperative diagnosis. The main reason for not reaching a definitive malignant diagnosis was sampling error due to small tumours less than 1 cm in diameter, irrespective of tumour subtype.

Surgical therapy of benign liver tumors

Benign liver tumors are being detected more frequently due to the widespread use of ultrasound and complementary methods and due to improvements in diagnostic accuracy. In the case of a reliable diagnosis of asymptomatic hemangioma or focal nodular hyperplasia surgery is not indicated. Hepatic adenoma of considerable size should be resected primarily based on the risk of rupture. Improvements in diagnostic imaging as well as the optimization of surgical procedures with extremely low complication rates permit an individualized management strategy founded on evidence-based algorithms. In the case of an equivocal diagnosis, we advocate low-risk tumor resection instead of tumor biopsy due to the inherent complication rates of hemorrhage or tumor-cell dissemination and possible misleading histology.

Fine needle aspiration cytology in young women with breast cancer diagnostic difficulties

Breast carcinoma is the most common malignancy in women worldwide. Though fine needle aspiration cytology (FNAC) plays an important role in preoperative diagnosis, there may be diagnostic delays in affected young women due to a lower index of suspicion. The files of the Departments of Pathology, Singapore General Hospital, Singapore, and Prince of Wales Hospital, Hong Kong, were searched for cases of breast carcinoma in women aged 35 years or less. Those with prior FNA procedures comprised our study group. The FNA smears were reviewed and classified into five categories: inadequate, benign, equivocal, suspicious, malignant. The findings were correlated with subsequent histology. Thirty-four women aged 35 years and below underwent 35 FNACs, with one woman having bilateral FNA procedures. Upon review, one (2.9%) was classified as inadequate, one (2.9%) benign, five (14.3%) equivocal, five (14.3%) suspicious, 21 (60%) malignant and slides were not available for review for two (5.6%) cases. For six benign and equivocal cytological diagnoses, subsequent histology disclosed pure ductal carcinoma in situ (DCIS, 1 case), mucocoele-like lesions with DCIS (2 cases), invasive and in situ ductal carcinoma with neuroendocrine features (1 case) and two cases of invasive ductal carcinoma. Diagnostic difficulties in cytological interpretation of aspirates from breast carcinoma in young women may lead to unwanted delays, which occurred in six (17.6%) of 34 women in our series. Low grade cancers posing a pitfall in cytological diagnosis have to be considered.

Candida and dysbacteriosis: A cytologic, population-based study of 100,605 asymptomatic women concerning cervical carcinogenesis

The objective of this study was to investigate whether the presence of vaginal Candida or dysbacteriosis predisposes women to an increased susceptibility for (pre)neoplasia over time. A retrospective, longitudinal, cohort study was performed and was conducted in a population of 100,605 women, each of whom had 2 smears taken over a period of 12 years as part of the Dutch Cervical Screening Program. From these women, a cohort of 1439 women with Candida and a cohort of 5302 women with dysbacteriosis were selected as 2 separate study groups. The control cohort consisted of women who had completely normal cervical smears (n = 87,903 women). These groups were followed retrospectively over time. The odds ratios (OR) for squamous abnormalities in the follow-up smear for the women in these 3 cohorts were established. The dysbacteriotic cohort was significantly more likely to have low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL+) in their follow-up smear (OR, 1.85; 95% confidence interval [95% CI], 1.28-2.67 and OR, 2.00; 95% CI, 1.31-3.05, respectively) compared with women in the control group. In contrast, the Candida cohort had no significantly increased or decreased risk of developing SIL. The equivocal diagnosis 'atypical squamous cells of undetermined significance' was rendered significantly more often in the follow-up smear of both study cohorts (Candida cohort: OR, 1.42; 95% CI, 1.03-1.95; dysbacteriotic cohort: OR, 1.44; 95% CI, 1.22-1.71). The results from this study indicated that the presence of Candida vaginalis was not associated with an increased risk for SIL over time. In contrast, women with dysbacteriosis had a significantly increased risk of developing (pre)neoplastic changes. These findings should be taken into account in further research concerning predisposing factors for cervical carcinogenesis.

The Brain in Children: Is Contrast Enhancement Really Needed after Obtaining Normal Unenhanced CT Results?

To retrospectively determine and compare the sensitivity and specificity of unenhanced and contrast material-enhanced computed tomography (CT) (reference standard) in the diagnosis of brain abnormalities and to evaluate any change in diagnosis that resulted from the contrast-enhanced study. This study was approved by the local research ethics board; the requirement for informed consent was waived. The authors reviewed the unenhanced and contrast-enhanced CT scans of the brain obtained in 353 children for indications other than trauma. There were 196 boys and 157 girls aged 0 months to 17.8 years. Scans were read independently by two pediatric neuroradiologists who were blinded to clinical information. The diagnosis for each scan was recorded according to the anatomic section (supratentorial, infratentorial, ventricles, and skull). The final diagnosis was classified as normal, abnormal, or equivocal. kappa Statistics, with 95% confidence intervals, were reported, and the sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Interreader agreement for different anatomic regions varied between good (kappa coefficient, 0.63) and very good (kappa coefficient, 0.88) for unenhanced and contrast-enhanced scans. Sensitivity, specificity, positive predictive value, and negative predictive value for unenhanced scans were 97%, 89%, 87%, and 97%, respectively. The use of contrast material led to a change in the original normal or equivocal diagnosis to an abnormal diagnosis for only five (2.7%) of the 183 normal unenhanced scans. Unenhanced CT of developing brains has high sensitivity and specificity in the diagnosis of pathologic findings. The use of intravenous contrast material after unenhanced CT of the brain in children did not change the diagnosis frequently.

358* Towards a consensus on the investigation and management of infants with an equivocal diagnosis following newborn screening for cystic fibrosis

358* Towards a consensus on the investigation and management of infants with an equivocal diagnosis following newborn screening for cystic fibrosis

The Role of Intra-Arterial Calcium Stimulation Test with Hepatic Venous Sampling (IACS) in the Management of Occult Insulinomas

Occult insulinomas remain a clinical challenge. Specifically designed protocols are necessary to aid detection and facilitate a focused pancreatic exploration. Seventeen non-multiple endocrine neoplasia (non-MEN) patients referred to this medical center in the past 10 years because of equivocal diagnosis, failure of previous operation or difficulty in localization for insulinomas were studied. A routine intra-arterial calcium stimulation test with venous sampling (IACS test) was done for lesion localization. An exploratory laparotomy with intraoperative ultrasound (IOUS) examinations was performed. Preoperative imaging (sonography, high-resolution computed tomography scan, and magnetic resonance imaging) found six insulinomas, and IOUS found an additional six in the pancreatic regions; all were compatibly indicated by the IACS test. The remaining five patients with occult lesions by IOUS were treated by 40% (1) or 60-70% (4) distal pancreatectomies when insulin gradients were demonstrated on calcium stimulation to the splenic or to the superior mesenteric artery, respectively, and nesidioblastosis was found in each pathology examination. There were no complications related to the arterial stimulation and venous sampling (ASVS) test. No patient had recurrent hyperinsulinism, permanent morbidity, or mortality from surgery. IACS test helps in the diagnosis of equivocal pancreatogenous hypoglycemia, indicating the pancreatic region of priority exploration and guiding a pancreatic resection.

The Natural History and Traditional Management of Appendicitis Revisited: Spontaneous Resolution and Predominance of Prehospital Perforations Imply That a Correct Diagnosis is More Important Than an Early Diagnosis

The principle of early exploration on wide indications in order to prevent perforation has been the guiding star for the management of patients with suspected appendicitis for over 100 years, dating back to a time when appendicitis was a significant cause of mortality. Since then there has been a dramatic decrease in mortality due to appendicitis. Emerging evidence calls for a new understanding of the natural history of untreated appendicitis. This motivates a reappraisal of the fundamental principles for the management of patients with suspected appendicitis. Analysis of epidemiologic and clinical studies that elucidate the natural history of appendicitis, i.e. the possibility of spontaneous resolution or the risk of progression to perforation, the determinants of the proportion of perforations and mortality, and the consequence of in-hospital delay. The results presented in a number of studies suggest that spontaneous resolution of appendicitis is common, that perforation can seldom be prevented, that the risk of perforation has been exaggerated and that in-hospital delay is safe. An alternative understanding of the inverse relationship between the proportion of negative explorations and perforation and the increasing proportion of perforation with length of time is presented, mainly explaining these findings by selection due to spontaneous resolution. Evidence suggests that spontaneous resolution of untreated, non-perforated appendicitis is common and that perforation can rarely be prevented and is associated with a lower increase in mortality than was previously thought. This motivates a shift in focus from the prevention of perforation to the early detection and treatment of advanced appendicitis. In order to minimize mortality, morbidity and costs avoidance of negative appendectomies is more important then preventing perforation. In patients with an equivocal diagnosis where advanced appendicitis is deemed less likely a correct diagnosis is more important than a rapid diagnosis. These patients can safely be managed by active observation with an improved diagnostic work-up under observation, which has consistently shown a low proportion of negative appendectomies without an increase in the proportion of perforations or morbidity. A high proportion of perforations can be explained by selection due to undiagnosed resolving appendicitis. The proportion of perforation is therefore a questionable measure of the quality of the management of patients with suspected appendicitis and should be used with caution.

Prospective Evaluation of Oral Gastrografin in Postoperative Small Bowel Obstruction

Orally administered gastrografin has been used for early resolution of postoperative small bowel obstruction (POSBO) and to reduce the need for surgery in various studies. However the studies have reported conflicting results as patients with complete obstruction and equivocal diagnosis of bowel strangulation were also included. We carried out a prospective study to evaluate the efficacy of gastrografin in patients with partial adhesive small bowel obstruction. Patients with suspected strangulation, complete obstruction, obstructed hernia, bowel malignancy, and radiation enteritis were excluded. Sixty-two patients with partial adhesive small bowel obstruction were given an initial trial of conservative management of 48 h. Thirty-eight patients improved within 48 h and the other 24 were given 100 ml of undiluted gastrografin through the nasogastric tube. In 22 patients the contrast reached the colon within 24 h. In the remaining two patients the contrast failed to reach the colon and these underwent surgery. The use of gastrografin avoided surgical intervention in 91.3% (22 of 24) patients who failed conservative management of POSBO. Gastrografin also decreased the overall requirement for surgical management of POSBO from the reported rate of 25 to 30% to 3.2% (2 of 62). Use of gastrografin in patients with partial POSBO helps in resolution of symptoms and avoids the need for surgical management in the majority of patients.

Passive Seeding in Metanephric Adenoma: A Review of Pseudometastatic Lesions in Perinephric Lymph Nodes

Lymph node involvement derived from a discrete neoplastic process fundamentally implies tumor malignancy. However, rarely, inconsequential passive transport of benign neoplastic cells to the lymph node can occur and may cause confusion as to the nature of the neoplasm (ie, malignant vs benign). We describe a 10-cm right renal metanephric adenoma incidentally discovered in a 30-year-old woman during cesarean section for a triplet pregnancy. Subsequent nephrectomy following an equivocal needle biopsy diagnosis showed histologic features classic for metanephric adenoma, including the lack of cytologic atypia and mitoses. Necrosis present in this lesion appeared to be secondary to tumor physical disruption. The tumor cells were positive for Wilms tumor 1 (WT1) antigen, pankeratin, and CD57, focally positive for epithelial membrane antigen, and negative for cytokeratin 7, cytokeratin 34betaE12, and CD56. Electron microscopy confirmed the tumor's epithelial nature, and cytogenetics revealed a diploid 46XX karyotype. The tumor proliferation index with Ki-67 was only 3% to 5% and the proliferating cell nuclear antigen index was 0%. A single, concurrently resected hilar lymph node contained scattered subcapsular, sinusoidal, and focally intralymphovascular psammoma bodies along with occasional adherent epithelial cells. These cells were highlighted by pankeratin but were nonreactive to WT1 antigen, similar to the nonviable cells in the primary tumor. Clinical surveillance and follow-up showed no disease recurrence 4 years after nephrectomy. We postulate that the lymph node inclusions found in this case represent passive transport of neoplastic cells to the lymph node following manipulation of the renal mass. We conclude that this phenomenon is understudied and underrecognized and can easily be mistaken for metastasis.

Diagnosis of appendicitis in adults by ultrasonography or computed tomography: A systematic review and meta-analysis

The use of ultrasonography and computed tomography (CT) in the diagnosis of appendicitis in adult patients was compared. Systematic review and meta-analysis of current evidence in two clinical situations: unselected nonpregnant, adult patients with symptoms of appendicitis, and more selective use in only those patients who still have an equivocal diagnosis subsequent to routine clinical investigations. Meta-analysis of eligible studies shows CT to have better sensitivity and specificity than ultrasound in both clinical situations. Application of these findings in clinical practice and/or policy would need to evaluate the better diagnostic performance of CT against its cost and availability. In addition, it is imperative that future studies be conducted in patient populations that are well-defined with respect to prior investigations. Sequelae of false-negative and false-positive diagnoses should also be evaluated.

P63 Immunohistochemistry in the distinction of adenoid cystic carcinoma from basaloid squamous cell carcinoma

Morphologic distinction of high-grade adenoid cystic carcinoma from basaloid squamous cell carcinoma can be difficult. Equivocal diagnoses can mislead treatment. We have investigated the possibility that immunohistochemical staining for the presence of p63, a novel epithelial stem-cell regulatory protein, could be a useful means of distinguishing these two neoplasms. Archival, routinely processed slides were subjected to citrate-based antigen retrieval, exposure to anti-p63 monoclonal 4A4, and developed with a streptavidin–biotin kit and diaminobenzidine as chromogen. p63 was detected in 100% of the adenoid cystic carcinomas (n=14) and 100% of basaloid squamous cell carcinomas (n=16). Basaloid squamous cell carcinomas consistently displayed diffuse p63 positivity, with staining of nearly 100% of tumor cells. In contrast, adenoid cystic carcinoma displayed a consistently compartmentalized pattern within tumor nests. Compartmentalization was manifested in two patterns: (1) selective staining of a single peripheral layer of p63-positive cells surrounding centrally located tumor cells that were p63-negative and (2) tumor nests consisting of multiple contiguous glandular/cribriform-like units of p63-positive cells surrounding or interspersed with p63-negative cells. p63 immunostaining constitutes a specific and accurate means of distinguishing adenoid cystic carcinoma from basaloid squamous cell carcinoma. p63 positivity in adenoid cystic carcinoma appears to be homologous to that seen in the basal and/or myoepithelial compartments of salivary gland and other epithelia, and may signify a stem-cell-like role for these peripheral cells. Diffuse p63 positivity in basaloid squamous cell carcinoma suggests dysregulation of p63-positive stem cells in poorly differentiated squamous carcinoma.