Thyroid FNAC: Causes of false-positive results.

In this paper, we aim to focus on false positive results in the evaluation of thyroid aspirations, covering cystic, inflammatory, follicular and oncocytic lesions, papillary carcinoma, and medullary carcinoma of thyroid. The recently described entity noninvasive follicular thyroid neoplasm with papillary-like nuclear features is also discussed detailing the impact of its introduction on the sensitivity and specificity of thyroid FNA, as well as the use of molecular tests for diagnostics. Medicolegal issues in relation to current practice in English law are also described.

Molecular pathology and thyroid FNA.

This review summarises molecular pathological techniques applicable to thyroid FNA. The molecular pathology of thyroid tumours is now fairly well understood. Molecular methods may be used as a rule-in test for diagnosis of malignancy in thyroid nodules, eg BRAF V600E point mutation, use of a seven-gene mutational panel (BRAF V600E, RAS genes, RET/PTC or PAX8/PPARG rearrangement), or as a comprehensive multigene next-generation sequencing panel, eg ThyroSeq v2. Molecular methods can also be applied as rule-out tests for malignancy in thyroid nodules, eg Afirma or ThyroSeq v2 or as markers of prognosis, eg TERT promoter mutation or other gene mutations including BRAF V600E, TP53 and AKT1, and as tests for newly defined tumour entities such as non-invasive follicular thyroid neoplasm with papillary like nuclei, or as a molecular marker(s) for targeted therapies. This review describes practical examples of molecular techniques as applied to thyroid FNA in routine clinical practice and the value of molecular diagnostics in thyroid FNA. It describes the range of molecular abnormalities identified in thyroid nodules and thyroid cancers with some practical applications of molecular methods to diagnosis and prognosis of thyroid nodules and thyroid cancer.

BRAF V600 co-testing is technically feasible in conventional thyroid fine needle aspiration (FNA) cytology smears and can reduce the need for completion thyroidectomy.

INTRODUCTION: While fine needle aspiration cytology (FNAC) is the mainstay of diagnosis in thyroid nodules, molecular markers of thyroid cancer have recently been shown to be of value in improving the diagnosis and reducing the rates of unnecessary surgery. METHOD: A technical method is presented for the assessment of the BRAF V600 gene mutation in thyroid cancer using a simple adaptation of a commercially available kit. After standard preparation and reporting of conventionally stained alcohol-fixed Papanicolaou or air-dried Giemsa-stained slides the coverslip is removed from one slide, the DNA is extracted and submitted for PCR analysis. RESULTS: Assessment of the BRAF V600 mutational status is feasible in very small quantities of DNA, requiring just greater than 5 ng per case from a single pre-stained FNA slide using this method. From the 14 cases examined thus far, one Thy4/Bethesda Class V case (suspicious of malignancy) has been identified with a BRAF V600 mutation and this patient, after multidisciplinary discussion, received a total thyroidectomy. CONCLUSION: Based on this methodology and other published results for the BRAF mutation, we believe that it is now feasible and cost effective for the UK NHS to BRAF co-test all Thy4/Bethesda Class V thyroid FNAs, as the additional cost of BRAF testing will still be much less than the cost of submitting all Thy4 (Bethesda Class V) patients to a partial and then a later completion thyroidectomy.

Rapid on-site assessment of specimens by biomedical scientists improves the quality of head and neck fine needle aspiration cytology.

OBJECTIVE: Immediate rapid on-site assessment (ROSA) of fine needle aspiration cytology (FNAC) specimens by biomedical scientists (BMS), the UK equivalent of cytotechnologists, or by pathologists may improve specimen quality and cellular adequacy rates for lymph node, head and neck and thyroid FNAC. The aim of this study was to evaluate the effect of introducing ROSA by BMS in an outpatient clinic setting. METHODS: The adequacy rate and sensitivity of histological diagnosis for lymph node, thyroid and salivary gland FNAC samples were determined before and after the introduction of BMS ROSA. The additional financial costs and time required to perform this service were also estimated. RESULTS: Thirty-one patients underwent ultrasound (US)-guided FNAC with ROSA and 151 without. ROSA reduced the number of FNAC insufficient in quality for diagnosis from 43% to 19% (P = 0.0194). The estimated additional cost for pathology per patient for ROSA was between £52.05 and £70.74, equivalent to €65.40/US $83.90 and €88.89/US $114.0, respectively, an increase of between 28% and 49% from the original cost. ROSA necessitated an additional 6 minutes clinic time per patient, reducing the number of patients that could be seen in an average clinic from 13 to 10 as well as requiring increased laboratory time for FNAC slide assessment. CONCLUSION: ROSA by suitably trained biomedical scientists and with appropriate consultant pathologist support can improve the quality of FNAC sampling for head and neck lesions. Although ROSA resulted in both additional financial and time costs, these are more than likely to be offset by a reduction in patients returning to clinic for repeat FNAC or undergoing unnecessary surgery.

Thyroid FNAC cytology: can we do it better?

This article reviews recent developments in thyroid fine needle aspiration cytology (FNAC). While thyroid nodules are common, carcinoma is comparatively rare. Although histological assessment is used in most studies as the benchmark, the differential diagnosis on cytology or histology is not always reproducible. The literature shows wide variations in criteria for inadequate thyroid FNAC and study inclusion or exclusion criteria. In-clinic assessment of specimen adequacy and in-clinic reporting of thyroid FNAC has become popular although the costs and resource implications of in-clinic thyroid FNAC assessment and reporting are substantial. Many centres continue to use conventional techniques although liquid-based cytology and ultrasound-guided FNAC are gaining in popularity. Standardized categorical systems for FNAC reporting can make results easier to understand for clinicians and give clear indications for therapeutic action. Multidisciplinary case review is also essential, especially when there is diagnostic uncertainty. While currently of limited use, molecular pathology testing holds out some promise for the future.

Recent Developments in the Pathology of Thyroid Cancer.

The histopathological features of thyroid cancers can be used to risk stratify patients, allowing prognostication and treatment decisions. A detailed accurate histological assessment by experienced pathologists working within a multidisciplinary context is crucial. Experience is also essential for interpretation of preoperative thyroid cytology specimens, which can be challenging. There is now more international harmonisation of numerical reporting systems for thyroid cytology. Understanding of the molecular basis of thyroid cancer has increased dramatically in recent years. Preoperative molecular pathology testing, when available, can refine cytological diagnosis to rule in or out for surgery, as well as assisting prognostication and enabling targeted treatment for thyroid tumours.

Prognostic relevance of extensive necrosis in renal cell carcinoma.

AIMS: Evidence suggests that the presence of tumour necrosis is an adverse prognostic factor in renal cell carcinoma (RCC). However, it has also been shown that tumour regression, a microscopic feature associated with necrosis, may be a favourable short term prognostic factor in RCC. METHODS: Pathology reports of 253 RCCs from 1992 to 2001 were reviewed, and identified 37 tumours with substantial macroscopic or microscopic necrosis. Microscopic pathology, TNM 1997 tumour stage, and clinical follow up were reviewed and correlated with pathological findings. Three cases were rejected because two were diagnosed at necropsy, and a third was the result of renal arterial embolisation. RESULTS: Twenty of the 34 cases showed <50% necrosis, 10 showed 50-94% tumour necrosis, and four showed >95% tumour necrosis. Follow up data were unavailable in three cases. Nine of the remaining 31 tumours progressed; six were group 3 tumours showing <50% necrosis, three were group 2 tumours showing 50-94% necrosis, and none was a group 1 tumour showing >95% necrosis. CONCLUSIONS: Extensive necrosis (>95% necrosis) is rare in RCC, accounting for only 1.6% of those diagnosed during eight years in this unselected hospital series. The microscopic pattern of necrosis was typical, requiring extensive tumour sampling for definitive tumour diagnosis. Although there were only four patients with extensive necrosis, none developed recurrent or metastatic carcinoma, or died from RCC. Although extensive (>95%) necrosis may imply better short term prognosis after adjusting for tumour pathological TNM stage, it is probably not a prognostic variable in RCC.

Ten-year results comparing mastectomy to excision and radiation therapy for ductal carcinoma in situ of the breast.

The 10-year results of 300 patients with ductal carcinoma in situ (DCIS) without microinvasion are reported; 167 treated with mastectomy and 133 treated with excision and radiation therapy. There was a significant difference in disease-free survival at 10 years, in favour of those treated with mastectomy, 98% versus 81% (P = 0.0004). Multivariate analysis confirmed nuclear grade as the only significant predictor of local recurrence (P = 0.02) or invasive local recurrence (P = 0.03) in patients with DCIS treated with excision and radiation therapy. There was no difference in breast cancer-specific survival or overall survival between the two treatment groups.

p53 protein expression in mammary ductal carcinoma in situ: relationship to immunohistochemical expression of estrogen receptor and c-erbB-2 protein.

The immunohistochemical expression of the p53 gene protein was examined in a consecutive series of 143 cases of pure ductal carcinoma in situ (DCIS) of the breast. Expression of wild-type and/or mutant p53 protein was detected in 36 (25.2%) of the cases examined, as evidenced by positive nuclear staining with the monoclonal antibody DO 7. Thirty-four (35.8%) of the large cell cases showed p53 protein expression compared with two (4.1%) of the small cell cases (chi 2 = 15.3 [df = 1], P < .001). p53 Protein expression also was associated with an increased histologic degree of necrosis, with a nearly significant association of negative tumor estrogen receptor status and p53 protein expression. No significant association of p53 protein expression and c-erbB-2 protein expression was seen. Immunohistochemical expression of p53 protein is present in approximately 25% of DCIS cases and is confined almost exclusively to large cell DCIS, a morphologic subtype of in situ breast carcinoma thought to be more biologically aggressive. Expression of p53 protein may be important in the neoplastic progression of DCIS, reflecting the acquisition of p53 gene mutations in large cell DCIS cases. Therefore, p53 may be implicated in mammary tumor evolution from in situ to invasive disease.

Spontaneous regression of renal cell carcinoma: a pitfall in diagnosis of renal lesions.

Two cases of renal cell carcinoma, both of which underwent extensive spontaneous regression, are reported. The first occurred in a 56 year old man, forming a well circumscribed renal cortical nodule which contained only very occasional foci of viable renal cell carcinoma with areas of hyalinisation and calcification, and with metaplastic ossification. The second lesion was removed from an 82 year old man, comprising a cystic cavity containing necrotic debris with only occasional viable foci of classical renal cell carcinoma. Spontaneous regression of renal cell carcinoma is a rare but recognised entity. These two cases emphasise the important differential diagnoses: metastatic secondary carcinomas, xanthogranulomatous pyelonephritis, and infective granulomatous conditions of the kidney. The importance of adequate tissue sampling of all renal nodules cannot be overemphasised in the processing for examination of lesions within the kidney.

Are renal microgranulomas related to inflammatory tubular destruction?

Two cases of renal microgranuloma formation are reported, one in a patient with known Crohn's disease and another in a case of acute renal allograft rejection. In both cases, the microgranulomas arose as a result of inflammatory tubular destruction, in a manner analogous to that seen in patients with ulcerative colitis arising adjacent to ruptured epithelial crypts in the large intestine. Microgranulomas may occur at multiple anatomical sites in Crohn's disease, although renal microgranulomas are very rare. Non-specific inflammatory tubular destruction should be considered as a cause of renal microgranuloma formation, in addition to systemic granulomatous diseases, such as tuberculosis, sarcoid, or Crohn's disease, when granulomas are seen in the presence of inflammatory tubular destruction in renal biopsies.

The importance of skip lesions in temporal arteritis.

AIM: To determine the frequency of skip lesions in an unselected series of temporal artery biopsies and compare the results with other series. METHODS: The study was a retrospective review of 102 consecutive temporal artery biopsies taken in a five year period (1992-1997) in one large hospital. RESULTS: 35 cases (34.3%) showed evidence of active cranial vasculitis with pathological evidence of inflammation of the intima or media, with or without giant cells. Three of these cases (8.5%) showed apparent skip lesions: normal intima, media, and adventitia in one segment while in other segments there was clear evidence of active vasculitis. Immunocytochemical stains for leucocyte common antigen (LCA) and CD15 were helpful in identifying the absence of intimal or medial inflammatory cell infiltrates within skip lesions. Skip lesions have been described in up to 28.3% of cases in some series, while others have not found evidence of skip lesions or have identified them in a much smaller percentage of cases. CONCLUSIONS: In this series skip lesions were relatively rare, accounting for 8.5% of cases of active vasculitis. The degree of inflammation in temporal arteritis is discontinuous. Immunostaining for inflammatory cells, for example LCA and CD15, may be helpful in identifying the presence of an inflammatory cell infiltrate in skip lesion segments of the temporal artery.

Pathology of ductal carcinoma in situ of the breast: current status.

Ductal carcinoma in situ (DCIS) now accounts for around 20-25% of mammographically detected breast cancers. There is strong evidence to show that classification schemes for DCIS should be based primarily on nuclear grade and necrosis as these two features have been shown to be prognostically important as well as having high interobserver reproducibility among pathologists. Newer classifications of DCIS that employ these features, such as the Van Nuys DCIS Classification, are of prognostic importance in predicting recurrence of DCIS after breast conservation and show high levels of reproducibility. For treatment of DCIS via breast conservation a high pre-operative diagnostic rate is desirable, only achievable via needle-guided core biopsy. If local excision without radiotherapy is to be given there is strong evidence to support the requirement for a 10 mm tumour-free margin. Assurance that a margin is tumour-free requires sequential specimen processing which is both time consuming and costly, but which can be justified in cost and morbidity terms as radiotherapy may not be required for those patients with a 10 mm tumour-free margin. Other methods of specimen examination involve examination of mammographically directed tissue slices or alternative methods of excision margin assessment such as "onion skinning" of the specimen. Endocrine therapy will doubtless become more important for adjuvant therapy of DCIS as well as chemoprophylaxis in the future.

Method of specimen fixation and pathological dissection of colorectal cancer influences retrieval of lymph nodes and tumour nodal stage.

INTRODUCTION: There is now evidence that meticulous specimen dissection may 'upstage' around one-quarter of colorectal cancers from node negative to node positive, although there is much debate as to how to achieve this: some authors prefer fat clearance techniques while others have opted for more conventional lymph-node retrieval with manual specimen 'breadknifing' and lymph-node palpation. While fat clearance is probably the optimum technique, it is time-consuming, costly and does not provide rapid diagnostic results. METHODS: A prospective pathological study of 50 colorectal cancer resections was conducted with 100 comparison cases, the study group receiving at least an additional 24-h fixation of the mesocolonic or mesorectal fat in 10% aqueous formaldehyde prior to specimen dissection. RESULTS: The percentage of node-negative colorectal cancer was significantly lower in the study group compared with the matched comparison group: (18) 36% compared with (55) 55% of comparison cases. CONCLUSIONS: Effective lymph-node retrieval techniques require mesocolic/mesorectal fat to be adequately fixed prior to pathological dissection. This study suggests that satisfactory lymph-node retrieval is possible without fat clearance, provided the mesenteric fat is suitably fixed prior to colorectal cancer specimen dissection.

Referrals for second opinion in surgical pathology: implications for management of cancer patients in the UK.

OBJECTIVE: To compare patterns of outgoing referral practice from one large district general hospital histopathology (cellular pathology) laboratory to other pathology laboratories. DESIGN: Referral cases for the relevant years were identified via hand searching of consultant referral files and from a central laboratory referral file. A comparison was made of the number and nature of pathology case referrals made to other laboratories in year 1990 with those made in year 1998. SETTING: Large district general hospital pathology laboratory in the UK. RESULTS: A statistically significant increase in the number of cases referred for a second opinion to an outside pathologist was noted, from 60 to 128 cases, representing an increase from 0.35 to 0.56% of total laboratory specimen workload (P=0.0034). In 36 (31.0%) of 116 cases from 1998 the diagnosis was altered, or a confident diagnosis was made where previously there was no definite diagnosis. Five cases with a benign in-house diagnosis had a malignant second opinion diagnosis and five cases with a malignant in-house diagnosis had a benign second opinion diagnosis. The largest single category of referred cases was for classification/grading of malignant lymphoma, comprising 27 (23%) of cases. The mean time delay between receipt of a specimen in the laboratory and issuing of the final report was 22 days (range 7-60 days). Only 25% of the referred cases were reported within 14 days. CONCLUSIONS: Referrals are an important component of pathology practice. In the UK much of this activity is performed on a 'grace and favour' basis between laboratories despite the fact that referral cases are often complex and time consuming for the recipient pathologist and laboratory. Histopathology referrals do not seem to be adequately costed and accounted for in interinstitutional service level agreements within the UK National Health Service.

Mural bridging lesions in colonic Crohn's disease.

A case of Crohn's colitis with mural bridging lesions is described. The bridging lesions comprised colonic-type mucosa, smooth muscle, nerve fibers, with foci of adipose tissue and fibrous connective tissue. The lesions arose from the muscularis propria proximal to colonic strictures and possibly due to diverticular outpouching of the colonic wall associated with increased intraluminal pressure, although the exact mechanism of their formation appears unclear. This entity has not been previously described in inflammatory bowel disease, to our knowledge. Bridging pseudopolyps are seen in ulcerative colitis and rarely in Crohn's disease but do not contain substantial amounts of smooth muscle and/or nerve fibers. We believe that the mural bridges described in this article represent residual muscularis propria at the site of diverticular formation due to long-standing Crohn's colitis. We speculate that the stricture formation seen distal to the site of the mural bridging lesions may have been an important factor in formation of the colonic diverticula and, hence, these lesions that we interpret as representing residual muscularis propria adjacent to sites of diverticular formation in long-standing Crohn's colitis.

Epidermal growth factor receptor expression in Barrett's esophagus.

Six cases of known Barrett's esophagus were examined immunohistochemically for the presence of epidermal growth factor receptor. All cases showed expression of epidermal growth factor receptor in intestinal metaplastic Barrett's epithelium, the most common form of Barrett's change. Expression of epidermal growth factor receptor may be important in neoplastic transformation in Barrett's esophagus, possibly by an autocrine mechanism. Alternatively, epidermal growth factor receptor expression in intestinal metaplastic Barrett's epithelium may represent a nonneoplastic regenerative phenomenon as seen at other sites within the gastrointestinal tract. Further larger studies are required to assess the clinical significance of these findings.

Colonic lymphoid hyperplasia in melanosis coli.

We describe the case of a patient with Rett syndrome, a syndrome characterized by progressive infant encephalopathy, developmental delay, dementia, autism, ataxia, microcephaly, spastic paraparesis, and autonomic neuropathy with constipation. At colonoscopy, multiple foci of tiny white, sessile, polypoid lesions were seen throughout the colon and rectum, mimicking the appearances of small hyperplastic or adenomatous polyps, associated with generalized melanosis coli. This is the first case to our knowledge describing melanosis coli in a patient with Rett syndrome. As melanosis pigment deposition is characteristically not seen in lymphoid tissue, the lymphoid tissue was identifiable at endoscopy as multiple white nodules mimicking generalized colonic polyposis throughout the colon. We discuss the likely mechanisms of lymphoid hyperplasia and coexistent melanosis coli in Rett syndrome.