What is your count? An observational study of lymph node counting in 2,028 colorectal cancer resections.

BACKGROUND: Lymph node status and lymph node count (LNC) are predictors of colorectal cancer outcome. Under-sampling of lymph nodes may lead to clinically relevant stage migration. METHODS: Colorectal cancer (CRC) cases with a synoptic report, accessioned 2012-2020 at a regional laboratory, were extracted and retrospectively studied. LNC, positive lymph node count (PLNC), tumour deposits present (TDpos), and 'y' (staging) prefix (YS) were retrieved and tabulated by pathologist using custom software. Statistical analyses were done with R. DATA AND RESULTS: The cohort had 2,543 CRC resections. Seventeen pathologists interpreted >50 cases (range: 56-356) each and collectively saw 2,074. After cases with unavailable data were purged, 2,028 cases remained with 43,996 lymph nodes, of which 2,637/43,996 were positive. 368 cases had a 'y' prefix, and 379 had TDpos. The 17 pathologists' median LNC/case was 19.0 (range: 14.0-24.0), and the mean PLNC per case was 1.4 (range: 1.0-2.0). Kruskal-Wallis rank sum tests showed there were differences in LNC (p<0.001) among pathologists; however, PLNC did not show this association (p = 0.2917). T-tests showed that mean LNC (p<0.001) and PLNC (p<0.035) differed between YS. 138 of 2,028 cases had less than the 12 LNC target. Logistic regression revealed a strong association between meeting the LNC target and pathologist (p<0.001) but TDpos was non-predictive (p = 0.4736). CONCLUSIONS: Positive lymph node call rate has a good consistency in the laboratory; however, lymph node count varies significantly between pathologists. Standardized counting criteria are needed to improve uniformity and could be aided by synoptic reporting data.

A 10-Year Review of Intraoral Salivary Gland Tumor Diagnoses: Diagnostic Challenges and Inter-Observer Agreement.

BACKGROUND: Salivary gland tumors (SGT) are a diverse group of neoplasms arising from the major and minor glands. The oral cavity is the most common site for minor SGT (IMSGT), and these lesions frequently pose a challenge to the pathologist due to overlapping histopathological features and limited material for analysis. Our objective was to determine specific clinical and histopathological features associated with challenges in IMSGT diagnoses and pathologists' agreement. METHODS: We conducted a retrospective analysis of 248 IMSGT received between 2010 and 2019. We evaluated the diagnostic challenge of the cases by stratifying according to whether a definitive, favored, or indeterminate (challenging) diagnosis was provided. Inter-observer agreement and concordance of biopsy diagnoses with the final diagnoses after tumor resection were evaluated. RESULTS: Of the 248 biopsies, 191 had a definitive diagnosis, 38 favored diagnoses, and 19 were indeterminate. The predominant diagnoses considered for the indeterminate category were pleomorphic adenoma/myoepithelioma (PA), polymorphous adenocarcinoma (PAC), adenoid cystic carcinoma (AdCC), and low-grade adenocarcinoma. Using multivariate analysis of clinical features, younger patient age, smaller tumor size, and larger biopsy size increased the likelihood of a definitive diagnosis (p = 0.014, p = 0.037, p = 0.012). The inter-observer agreement for 68 representative cases was moderate overall (Fleiss's Kappa 0.575) and good for the 40 cases with a definitive diagnosis (Fleiss's Kappa 0.66). Sixty-five biopsy diagnoses were matched with corresponding tumor resection diagnoses and found to show a good concordance (Cramer's V test 0.76). The discordant diagnoses predominantly involved PA, carcinoma exPA, PAC, AdCC, and adenocarcinoma NOS. CONCLUSION: Diagnostic challenges in IMSGT incisional biopsies were infrequent, especially if multiple pathologists were consulted. PA, PAC, AdCC, and adenocarcinoma NOS were the histologic types more commonly posing diagnostic challenges. Younger patient age, smaller tumor size, and larger biopsy are associated with a definitive diagnosis. This data highlights the importance of appropriate sampling in IMSGT.

Gastric Schwannoma as an Important and Infrequent Differential Diagnosis of Gastric Mesenchymal Tumours: A Case Report and Review of Literature.

The spectrum for gastrointestinal tract mesenchymal tumours includes leiomyomas, leiomyosarcomas, gastrointestinal stromal tumours (GISTs) and schwannomas. Schwannomas (also known as neuroma, neurilemmomas or neurinomas of Verocay) are well-known slow-growing, benign neoplasms that originate from nerve plexuses within a Schwann cell sheath. They can arise anywhere along the course of the peripheral nerve and are frequently reported around the head and neck, brachial plexus and along the gastrointestinal tract. Usually, these tumours are detected as solitary; however, they can occur at multiple sites around the body. Schwannomatosis (multiple schwannomas) is usually associated with neurofibromatosis type 2; the pathogenesis is triggered by mutations of the neurofibromatosis 2 tumour suppressor gene resulting in a loss of its function. Solitary gastric schwannomas are rare lesions that arise from the nerve plexus of the gastric wall. Frequently they are detected incidentally or may present with nonspecific abdominal pain or bleeding. This paper reports the case of a 79-year-old patient diagnosed with gastric schwannoma after presenting with abdominal pain. Gastric schwannomas should be taken into consideration while making a differential diagnosis of lesions that are gastric mesenchymal tumours, which span a broad spectrum. Gastric schwannomas are typically benign, considerably less common than gastric GISTs, and have an excellent prognosis following excision.

Evolution of anatomic pathology workload from 2011 to 2019 assessed in a regional hospital laboratory via 574,093 pathology reports.

OBJECTIVE: Quantify changes in workload in relation to the anatomic pathologist workforce. METHODS: In house pathology reports for cytology and surgical specimens from a regional hospital laboratory over a nine- year period (2011-2019) were analyzed, using custom computer code. Report length for the diagnosis+microscopic+synoptic report, number of blocks, billing classification (L86x codes), billings, national workload model (L4E 2018), regional workload model (W2Q), case count, and pathologist workforce in full-time equivalents (FTEs) were quantified. Randomly selected cases (n = 1,100) were audited to assess accuracy. RESULTS: The study period had 574,093 pathology reports that could be analyzed. The coding accuracy was estimated at 95%. From 2011 to 2019: cases/year decreased 6% (66,056 to 61,962), blocks/year increased 20% (236,197 to 283,751), L4E workload units increased 23% (165,276 to 203,894), W2Q workload units increased 21% (149,841 to 181,321), report lines increased 19% (606,862 to 723,175), workforce increased 1% (30.42 to 30.77 FTEs), billings increased 13% ($6,766,927 to $7,677,109). W2Q in relation to L4E underweights work in practices with large specimens by up to a factor of 2x. CONCLUSIONS: Work by L4E for large specimens is underrated by W2Q. Reporting requirements and pathology work-up have increased workload per pathology case. Work overall has increased significantly without a commensurate workforce increase. The significant practice changes in the pathology work environment should prompt local investment in the anatomic pathology workforce.

Feasibility and Performance of Elastin Trichrome as a Primary Stain in Colorectal Cancer Resection Specimens: Results of an Interobserver Variability Study.

Venous invasion (VI) is a powerful prognostic factor in colorectal cancer (CRC) that is widely underreported. The ability of elastin stains to improve VI detection is now recognized in several international CRC pathology protocols. However, concerns related to the cost and time required to perform and evaluate these stains in addition to routine hematoxylin and eosin (H&E) stains remains a barrier to their wider use. We therefore sought to determine whether an elastin trichrome (ET) stain could be used as a "stand-alone" stain in CRC resections, by comparing the sensitivity, accuracy, and reproducibility of detection of CAP-mandated prognostic factors using ET and H&E stains. Representative H&E- and ET-stained slides from 50 CRC resections, including a representative mix of stages and prognostic factors, were used to generate 2 study sets. Each case was represented by H&E slides in 1 study set and by corresponding ET slides from the same blocks in the other study set. Ten observers (3 academic gastrointestinal [GI] pathologists, 4 community pathologists, 3 fellows) evaluated each study set for CAP-mandated prognostic factors. ET outperformed H&E in the assessment of VI with respect to detection rates (50% vs. 28.6%; P<0.0001), accuracy (82% vs. 59%, P<0.0001), and reproducibility (k=0.554 vs. 0.394). No significant differences between ET and H&E were observed for other features evaluated. In a poststudy survey, most observers considered the ease and speed of assessment at least equivalent for ET and H&E for most prognostic factors, and felt that ET would be feasible as a stand-alone stain in practice. If validated by others, our findings support the use of ET, rather than H&E, as the primary stain for the evaluation of CRC resections.

Radical chest wall resection and hyperfractionated accelerated radiotherapy for radiation-associated angiosarcoma of the breast: A safe and effective treatment strategy.

Radiation-associated angiosarcomas (RAS) of the breast are vascular tumors arising in a previous radiation field for primary breast cancer. They occur rarely but confer a high probability of local recurrence (LR) and poor prognosis. A wide range of treatment strategies exists due to limited evidence, and although resection is the definitive treatment, LR rates remain high. It has been suggested hyperfractionated accelerated radiotherapy (HART) has the potential to prevent LR. The sarcoma group at the Juravinski Cancer Centre (JCC) reports our experience of nine patients treated with radical resection and adjuvant HART. This is one of the largest reported cohorts we are aware of to receive this treatment. The JCC pathologic data base was reviewed between the year 2006-2015 for patients with RAS. Patients who received radical surgery and immediate HART were eligible. Patients underwent radical chest wall resection and en bloc mastectomy. Radiotherapy was then delivered to 4500 cGy in 45 fractions three times daily using parallel opposed photon beams and electron patching, or volumetric modulated arc therapy. Primary outcome was recurrence-free survival in months, and records were reviewed for descriptive reports of toxicity. We compared our results to other institutions experience with surgery alone or other adjuvant therapies. Median follow-up was 19 months (range 3-41 months). One of nine patients developed LR and developed metastasis, one died of other causes, and seven are alive with no recurrent disease. There were seven reports of mild skin toxicity during treatment. One patient developed chronic wound healing complications which eventually resolved and one patient developed asymptomatic radiation osteitis of a rib. On the basis of our experience at the JCC, we recommend treatment with radical chest wall resection and adjuvant HART to prevent recurrence in RAS patients. As demonstrated in our patients, the large normal tissue volume irradiated is tolerable with in combination with small fraction sizes, and no major toxicities were seen. Further investigation into adjuvant therapy regimens and prospective studies are required to reach consensus on optimal treatment for this disease.

A Case of Patch Stage of Kaposi's Sarcoma and Discussion of the Differential Diagnosis.

A 55 year old HIV positive male had a skin lesion biopsy which showed atypical vascular proliferation within the superficial and deep dermis with mild atypia of lining endothelial cells. A sparse lymphoplasmacytic infiltrate surrounding the irregular vascular channels was noted. Immunohistochemistry highlighted the atypical blood vessels with the vascular markers CD31, CD34 and Factor VIII. The differential diagnosis included unusual vascular or lymphatic proliferations, stasis dermatitis, kaposiform hemangioendothelioma, progressive lymphangioma and angiosarcoma with focal Kaposi's sarcoma features. Characteristic human herpes virus-8 positive staining helped support the diagnosis of patch stage of Kaposi's sarcoma. Herein, we discuss the case findings, differential diagnosis and characteristic histological findings associated with the patch stage of Kaposi's sarcoma which can be an elusive diagnosis.

Angiosarcoma of the adrenal gland with concurrent contralateral advanced renal cell carcinoma: A diagnostic and management dilemma.

Angiosarcoma is a rare high-grade malignant neoplasm with poor clinical outcome and survival rates, occurring most commonly in the skin and soft tissue. It is composed of neoplastic cells that demonstrate endothelial differentiation. The diagnosis of angiosarcoma can be difficult due to its pathohistologic presentation as a poorly differentiated neoplasm with associated secondary changes. We report a case of angiosarcoma of the adrenal gland with concurrent contralateral renal cell carcinoma (RCC) and renal vein thrombus. The presumptive clinical diagnosis was metastatic renal cell carcinoma to the contralateral adrenal gland. Pathohistologic evaluation demonstrated massive hematoma associated with intravascular papillary endothelial hyperplasia (IPEH)-like features. We discuss the pathohistological features used to ascertain a diagnosis of angiosarcoma in the presence of IPEH-like changes and differentiate it from reactive vascular proliferation seen in IPEH (Masson's tumour).

Case report of a rare complication of open-heart surgery masquerading as a gunshot wound: an autopsy diagnosis.

INTRODUCTION: Poststernotomy mediastinitis is a rare feared sequelae of open-heart surgery with low incidence of 1% to 3% but a high mortality rate (10%-35%). Poststernotomy mediastinitis can in uncommon instances give rise to sternocutaneous fistulas in 0.25% to 10% of cases. Although scant reports have documented prosthetic valve endocarditis occurring in a setting of deep sternal wire infections, it is an infrequent but well-documented fatal complication of valvular replacement surgery. CASE REPORT: A 52-year-old male smoker with aortic valve replacement (2011), on Coumadin and Monocor, was found dead on September 2013 with a hole along a surgical scar over the sternum, masquerading as a gunshot wound. Chest radiograph revealed no foreign body, and no evidence of homicidal/suicidal or accidental cause was found at autopsy. Examination revealed a chronic fistulous tract from a deep sternal wire infection to the skin, in addition to a chronic sinus tract eroding into the root of the aorta with recent prosthetic valve endocarditis. DISCUSSION: To our knowledge, this is the first case report documenting poststernotomy mediastinitis causing a simultaneous occurrence of sternocutaneous fistula and prosthetic valve endocarditis. Either of these 2 exceptional but lethal complications would have sufficed as the cause of death.

S100A7 overexpression is a predictive marker for high risk of malignant transformation in oral dysplasia.

Early detection of oral lesions (OLs) at high risk of cancer development is of utmost importance for intervention. There is an urgent unmet clinical need for biomarkers that allow identification of high-risk OLs. Recently, we identified and verified a panel of five candidate protein biomarkers namely S100A7, prothymosin alpha, 14-3-3ζ, 14-3-3σ and heterogeneous nuclear ribonucleoprotein K using proteomics to distinguish OLs with dysplasia and oral cancers from normal oral tissues. The objective of our study was to evaluate the potential of these candidate protein biomarkers for identification of oral dysplastic lesions at high risk of cancer development. Using immunohistochemistry, we analyzed expressions of these five candidate protein biomarkers in 110 patients with biopsy-proven oral dysplasia and known clinical outcome and determined their correlations with p16 expression and HPV 16/18 status. Kaplan-Meier survival analysis showed reduced oral cancer-free survival (OCFS) of 68.6 months (p = 0.007) in patients showing cytoplasmic S100A7 overexpression when compared to patients with weak or no S100A7 immunostaining in cytoplasm (mean OCFS = 122.8 months). Multivariate Cox regression analysis revealed cytoplasmic S100A7 overexpression as the most significant candidate marker associated with cancer development in dysplastic lesions (p = 0.041, hazard ratio = 2.36). In conclusion, our study suggested the potential of S100A7 overexpression in identifying OLs with dysplasia at high risk of cancer development.

Secretome proteins as candidate biomarkers for aggressive thyroid carcinomas.

Using proteomics in tandem with bioinformatics, the secretomes of nonaggressive and aggressive thyroid carcinoma (TC) cell lines were analyzed to detect potential biomarkers for tumor aggressiveness. A panel of nine proteins, activated leukocyte cell adhesion molecule (ALCAM/CD166), tyrosine-protein kinase receptor (AXL), amyloid beta A4 protein, amyloid-like protein 2, heterogeneous nuclear ribonucleoprotein K, phosphoglycerate kinase 1, pyruvate kinase isozyme M2, phosphatase 2A inhibitor (SET), and protein kinase C inhibitor protein 1 (14-3-3 zeta) was chosen to confirm their expression in TC patients' sera and tissues. Increased presurgical circulating levels of ALCAM were associated with aggressive tumors (p = 0.04) and presence of lymph node metastasis (p = 0.018). Increased serum AXL levels were associated with extrathyroidal extension (p = 0.027). Furthermore, differential expression of amyloid beta A4 protein, AXL, heterogeneous nuclear ribonucleoprotein K, phosphoglycerate kinase 1, pyruvate kinase muscle isozyme M2, and SET was observed in TC tissues compared to benign nodules. Decreased nuclear expression of AXL can detect malignancy with 90% specificity and 100% sensitivity (AUC = 0.995, p < 0.001). In conclusion, some of these proteins show potential for future development as serum and/or tissue-based biomarkers for TC and warrant further investigation in a large cohort of patients.

Predictive value of metastatic cervical lymph node ratio in papillary thyroid carcinoma recurrence.

BACKGROUND: The purpose of this study was to determine whether the proportion of metastatic cervical lymph nodes resected (metastatic lymph node ratio [MLNR]) predicted papillary thyroid carcinoma (PTC) recurrence, and whether MLNR could alter the predictive ability of TNM nodal classification for recurrence in PTC. METHODS: We conducted a retrospective review of patients with PTC who underwent a total or near-total thyroidectomy with at least 1 lymph node removed at our institution. RESULTS: Of 253 patients, 35 (13.8%) developed recurrent disease. The total MLNR (ratio between total metastatic lymph nodes and total number of lymph nodes resected) independently predicted PTC recurrence (odds ratio [OR], 1.024; 95% confidence interval [CI], 1.010-1.039; p = .001). In receiver operating characteristic (ROC) curve analysis, TNM nodal classification with total MLNR had greater accuracy in predicting PTC recurrence than did TNM nodal classification alone (0.726 and 0.675, respectively). CONCLUSION: MLNR is an independent predictor of PTC recurrence and enhances the predictive value of TNM nodal classification.

Activated leukocyte cell adhesion molecule is a marker for thyroid carcinoma aggressiveness and disease-free survival.

BACKGROUND: Currently, there are no protein biomarkers for aggressive subtypes of thyroid carcinomas (TC) in clinical use that would allow for early detection and patient management. We hypothesized that activated leukocyte cell adhesion molecule (ALCAM or CD166) expression in thyroid tissues will reveal ALCAM to be a potential diagnostic and/or prognostic marker for TC aggressiveness. METHODS: Forty-five benign and 158 malignant thyroid tissues were analyzed for ALCAM expression using immunohistochemistry. ALCAM expression was correlated with different subtypes and clinicopathological features of TC, as well as patient disease-free survival. RESULTS: Combined membranous and cytoplasmic (total) expression of ALCAM was significantly reduced in patients with poorly/undifferentiated (aggressive) TC as compared to well-differentiated (nonaggressive) tumors (p<0.001; area-under-curve=0.865, sensitivity=82%, specificity=74%). The decreased ALCAM expression in TC correlated significantly with extrathyroidal extension, distant metastasis, and TC histotype. Notably, Kaplan-Meier survival analysis for follow-up data of 134 patients revealed significantly reduced disease-free survival for patients with TC with decreased ALCAM membranous, cytoplasmic, and total expression. Median survival of patients with decreased cytoplasmic ALCAM expression was 6 years, as compared to 13.7 years for patients with higher ALCAM expression (p<0.001). CONCLUSION: ALCAM has the potential to serve as a diagnostic and prognostic biomarker for aggressive TC. This protein can be taken forward for analysis in sera of patients with TC to determine its applicability as a minimally invasive serum biomarker for TC aggressiveness and patient disease-free survival.

Immunohistochemical analysis based Ep-ICD subcellular localization index (ESLI) is a novel marker for metastatic papillary thyroid microcarcinoma.

BACKGROUND: Thyroid cancer is among the fastest growing malignancies; almost fifty-percent of these rapidly increasing incidence tumors are less than or equal to 1cm in size, termed papillary thyroid microcarcinoma (PTMC). The management of PTMC remains a controversy due to differing natural history of these patients. Epithelial cell adhesion molecule (EpCAM) is comprised of an extracellular domain (EpEx), a single transmembrane domain and an intracellular domain (Ep-ICD). Our group reported nuclear Ep-ICD correlated with poor prognosis in thyroid cancer (Ralhan et al., BMC Cancer 2010,10:331). Here in, we hypothesized nuclear and cytoplasmic accumulation of Ep-ICD and loss of membranous EpEx may aid in distinguishing metastatic from non-metastatic PTMC, which is an important current clinical challenge. To test our hypothesis, Ep-ICD and EpEx expression levels were analyzed in PTMC and the staining was correlated with metastatic potential of these carcinomas. METHODS: Thirty-six PTMC patients (tumor size 0.5 - 1cm; metastatic 8 cases and non-metastatic 28 cases) who underwent total thyroidectomy were selected. The metastatic group consisted of patients who developed lymph node or distant metastasis at diagnosis or during follow up. The patients' tissues were stained for Ep-ICD and EpEx using domain specific antibodies by immunohistochemistry and evaluated. RESULTS: PTMC patients with metastasis had higher scores for nuclear and cytoplasmic Ep-ICD immunostaining than the patients without metastasis (1.96 ± 0.86 vs. 1.22 ± 0.45; p = 0.007 and 5.37 ± 0.33 vs. 4.72 ± 1.07; p = 0.016, respectively). Concomitantly, the former had lower scores for membrane EpEx than the non-metastatic group (4.64 ± 1.08 vs. 5.64 ± 1.51; p = 0.026). An index of aggressiveness, Ep-ICD subcellular localization index (ESLI), was defined as sum of the IHC scores for accumulation of nuclear and cytoplasmic Ep-ICD and loss of membranous EpEx; ESLI = [Ep - ICDnuc + Ep - ICDcyt + loss of membranous EpEx]. Notably, ESLI correlated significantly with lymph node metastasis in PTMC (p = 0.008). CONCLUSION: Nuclear and cytoplasmic Ep-ICD expression and loss of membranous EpEx were found to correlate positively with metastasis in PTMC patients. In addition, ESLI had the potential to identify metastatic behavior in PTMC which could serve as a valuable tool for solving a current dilemma in clinical practice.

An Ep-ICD based index is a marker of aggressiveness and poor prognosis in thyroid carcinoma.

BACKGROUND: Nuclear accumulation of the intracellular domain of epithelial cell adhesion molecule (Ep-ICD) in tumor cells was demonstrated to predict poor prognosis in thyroid carcinoma patients in our earlier study. Here, we investigated the clinical significance of Ep-ICD subcellular localization index (ESLI) in distinguishing aggressive papillary thyroid carcinoma (PTC) from non-aggressive cases. METHODS: Using domain specific antibodies against the intracellular (Ep-ICD) and extracellular (EpEx) domains of epithelial cell adhesion molecule, 200 archived tissues from a new cohort of patients with benign thyroid disease as well as malignant aggressive and non aggressive PTC were analyzed by immunohistochemistry (IHC). ESLI was defined as sum of the IHC scores for accumulation of nuclear and cytoplasmic Ep-ICD and loss of membranous EpEx; ESLI = [Ep-ICD(nuc) + Ep-ICD(cyt) + loss of membranous EpEx]. RESULTS: For the benign thyroid tissues, non-aggressive PTC and aggressive PTC, the mean ESLI scores were 4.5, 6.7 and 11 respectively. Immunofluorescence double staining confirmed increased nuclear Ep-ICD accumulation and decreased membrane EpEx expression in aggressive PTC. Receiver-operating characteristic (ROC) curve analysis showed an area under the curve (AUC) of 0.841, 70.2% sensitivity and 83.9% specificity for nuclear Ep-ICD for differentiating aggressive PTC from non-aggressive PTC. ESLI distinguished aggressive PTC from non-aggressive cases with improved AUC of 0.924, 88.4% sensitivity and 85.5% specificity. Our study confirms nuclear accumulation of Ep-ICD and loss of membranous EpEx occurs in aggressive PTC underscoring the potential of Ep-ICD and ESLI to serve as diagnostic markers for aggressive PTC. Kaplan Meier survival analysis revealed significantly reduced disease free survival (DFS) for ESLI positive (cutoff >10) PTC (p<0.05), mean DFS=133 months as compared to 210 months for patients who did not show positive ESLI. CONCLUSION: ESLI scoring improves the identification of aggressive PTC and thereby may serve as a useful index for defining aggressiveness and poor prognosis among PTC patients.

Biotinidase is a novel marker for papillary thyroid cancer aggressiveness.

Biotinidase was identified in secretome analysis of thyroid cancer cell lines using proteomics. The goal of the current study was to analyze the expression of biotinidase in thyroid cancer tissues and fine needle aspiration (FNA) samples to evaluate its diagnostic and prognostic potential in thyroid cancer. Immunohistochemical analysis of biotinidase was carried out in 129 papillary thyroid cancer (PTC, 34 benign thyroid tissues and 43 FNA samples and correlated with patients' prognosis. Overall biotinidase expression was decreased in PTC compared to benign nodules (p = 0.001). Comparison of aggressive and non-aggressive PTC showed decrease in overall biotinidase expression in the former (p = 0.001). Loss of overall biotinidase expression was associated with poor disease free survival (p = 0.019, Hazards ratio (HR) = 3.1). We examined the effect of subcellular compartmentalization of nuclear and cytoplasmic biotinidase on patient survival. Decreased nuclear expression of biotinidase was observed in PTC as compared to benign tissues (p<0.001). Upon stratification within PTC, nuclear expression was reduced in aggressive as compared to non-aggressive tumors (p<0.001). Kaplan-Meier survival analysis showed significant association of loss of nuclear biotinidase expression with reduced disease free survival (p = 0.014, HR = 5.4). Cytoplasmic biotinidase expression was reduced in aggressive thyroid cancers in comparison with non-aggressive tumors (p = 0.002, Odds ratio (OR) = 0.29) which was evident by its significant association with advanced T stage (p = 0.003, OR = 0.28), nodal metastasis (p<0.001, OR = 0.16), advanced TNM stage (p<0.001, OR = 0.21) and extrathyroidal extension (p = 0.001, OR = 0.23). However, in multivariate analysis extrathyroidal extension emerged as the most significant prognostic marker for aggressive thyroid carcinomas (p = 0.015, HR = 12.8). In conclusion, loss of overall biotinidase expression is a novel marker for thyroid cancer aggressiveness.