Dermatitis, cellulitis, and osteomyelitis caused by Aspergillus nidulans in a horse with pituitary pars intermedia dysfunction.

Clinical and histologic examination of a 12-y-old client-owned Quarter Horse gelding with pituitary pars intermedia dysfunction revealed dermatitis, cellulitis, and osteomyelitis caused by Aspergillus nidulans, confirmed by a PCR assay. This novel presentation of a fungal disease in a horse was characterized by aggressive local invasion and failure to respond to all medical therapy attempted over a 1-y period. Treatments included systemic and topical antifungals, anti-inflammatories, and use of cellular matrices. Surgical excision was not attempted but should be strongly considered early in the disease process in similar cases if clean margins can be achieved. Postmortem findings were of locally aggressive disease with no dissemination.

Case Report: Giant Multiloculated Pseudocystic Jejunal Leiomyosarcoma in a Dog: Atypical Morphologic Features of Canine Intestinal Leiomyosarcoma.

A 10-year-old intact female Rottweiler dog weighing 29 kg presented with 2 days history of vomiting, anorexia, and lethargy to KonKuk University Teaching Hospital, Seoul, South Korea. Ultrasonography and computed tomography (CT) scannings revealed a well-demarcated, large mass (29 × 19 × 11 cm) with numerous fluid-filled cavities. Metastases to adjacent lymph nodes were also identified on CT. This large mass and the affected intestinal segments were excised for palliative purposes. Postoperatively, the dog recovered uneventfully without any complications. The cut surface of the mass showed an exophytic growth pattern of multiloculated cystic lesions filled with serosanguineous fluid, large cavities filled with necrotic exudate, and fistulous connections between the intestinal lumen and the necrotic cavity in the mass. On histopathology, the mass was a spindle cell neoplasm expanding from the jejunal muscular layer and with pseudocystic changes. Additional immunohistochemical analysis using antibodies against smooth muscle actin, desmin, and CD-117 demonstrated that the mass was consistent with a leiomyosarcoma. Six months post-operatively, plain radiography revealed an abdominal mass, suspected to be recurrence from jejunal leiomyosarcoma. The owner decided to euthanize the dog due to financial constraints. This case report describes the atypical morphology and clinical progression of a large canine jejunal leiomyosarcoma, which had similar clinical features as those of human leiomyoma and leiomyosarcoma.

Equine Protozoal Myeloencephalitis associated with Neospora caninum in a USA captive bred zebra (Equus zebra).

A 6-year-old female captive zebra (Equus zebra) had a three-year history of slow progressive neurologic signs that recently worsened with hind limb ataxia, head tilt, and circling. Gross examination including the brain and spinal cord were unremarkable. On histopathology, the brain and brainstem had multiple random areas of severe lymphoplasmacytic meningoencephalitis associated with numerous 15-25 µm in diameter protozoal cysts with a discernible outer wall containing numerous 2 × 4 µm oval to crescent-shaped organisms. Immunohistochemistry and PCR identified the presence of Neospora organisms associated with the lesions. Equine protozoal myeloencephalitis (EPM) is generally associated with Sarcocystis neurona or less commonly Neospora hughesi. Molecular characterization revealed the first case of EPM associated with Neospora caninum in an equid as confirmed by DNA analysis.

Intradiploic epidermoid cyst in a dog.

CASE DESCRIPTION: A 10-year-old 7-kg (15.4-lb) neutered male Shih Tzu was referred for evaluation because of a sudden onset of dullness and intermittent vomiting of 1 to 2 weeks' duration. Two days prior to evaluation, clinical signs had worsened and 1 seizure was reported. CLINICAL FINDINGS: A 3.5 × 2.5-cm soft, dome-shaped mass of the right occipital region of the head was noted on physical examination. Radiography and CT confirmed the presence of the mass and indicated its intra- and extracranial expansion. The MRI images showed compression of the cerebellum by the mass, with distinct margins of hypointensity on both T1- and T2-weighted images. TREATMENT AND OUTCOME: Surgery was performed, and the mass was completely excised. The dog had mild ataxia, hypermetria, and head tremors after surgery. Histologic examination of the mass yielded a diagnosis of intradiploic epidermoid cyst. On examination 3 weeks after surgery, the previous neurologic signs had resolved. On examination 25 months after surgery, the dog remained free of clinical signs. CLINICAL RELEVANCE: The present report described the clinical signs, diagnostic imaging results, and successful surgical removal of an intradiploic epidermoid cyst in a dog. Long-term prognosis may be good with complete removal of intradiploic epidermoid cysts in dogs.

FIRST REPORT OF ADENOVIRAL HEMORRHAGIC DISEASE IN THREE MULE DEER (ODOCOILEUS HEMIONUS) IN ARIZONA.

This study presents the gross and histopathological findings of adenoviral hemorrhagic disease (AHD) in two yearling and one adult mule deer (Odocoileus hemionus). These cases represent the first known outbreak of deer adenovirus (Odocoileus adenovirus 1) in Arizona. Over the span of a month, three female captive mule deer were submitted to Midwestern University's Animal Health Institute for postmortem examination. All of these deer were from the same deer farm and historical findings were similar, consisting of acute presentation of hemorrhagic diarrhea and sudden death. Grossly and histopathologically, all cases had severe pulmonary edema and hemorrhagic enteritis. Additionally, two of the three cases had low numbers of large amphophilic intranuclear inclusions expanding endothelial cells within the small intestine and lungs. Viral PCR of pooled small intestine, lung, and spleen from each of the three cases were positive for deer adenovirus and negative for blue tongue and epizootic hemorrhagic disease.

Multiple cutaneous plasmacytosis with multilobated (clover-leaf shaped) nuclei cells in a dog.

A 12-year-old female Shih-tzu dog was presented with a 2-month history of cutaneous non-pruritic multiple ulcerated or crusted nodules of less than 1.5 cm in diameter on eyelids, lips, abdomen, groin, thighs and perianal region. Several diagnostic tests were performed, including fine needle aspiration and skin biopsy of the cutaneous nodules. Cytologic interpretation was round cell neoplasm with multilobated (clover-leaf shaped) nuclei. Histopathology revealed round neoplastic cells with prominent anisocytosis and anisokaryosis, and numerous mitotic figures; however, the origin of the cells was not identified. Immunohistochemical evaluation indicated that these cells were positive for CD79a and MUM-1, but negative for CD3, CD20 and Pax 5. The patient was treated with chemotherapy, and the skin condition improved. Despite good response to chemotherapy, the patient was euthanized due to poor general health.

Light-Activated Tissue-Integrating Sutures as Surgical Nanodevices.

Sutures are typically the primary means of soft tissue repair in surgery and trauma. Despite their widespread use, sutures do not result in immediate sealing of approximated tissues, which can result in bacterial infection and leakage. Nonabsorbable sutures and staples can be traumatic to tissue, and the trauma can be exacerbated by their subsequent removal. Use of cyanoacrylate glues is limited because of their brittleness and toxicity. In this work, laser-activated tissue-integrating sutures (LATIS) are described as novel nanodevices for soft tissue approximation and repair. Incorporation of gold nanorods within fibers generated from collagen result in LATIS fibers which demonstrate robust photothermal responses following irradiation with near infrared laser light. Compared to conventional sutures, LATIS fibers result in greater biomechanical recovery of incised skin in a mouse model of skin closure after spine surgeries. Histopathology analyses show improved repair of the epidermal gap in skin, which indicate faster tissue recovery using LATIS. The studies indicate that LATIS-facilitated approximation of skin in live mice synergizes the benefits of conventional suturing and laser-activated tissue integration, resulting in new approaches for faster sealing, tissue repair, and healing.

Molecular Detection of Equus caballus Papillomavirus Type 2 in Genital Swabs From Healthy Horses in the Republic of Korea.

Equus caballus papillomavirus type 2 (EcPV-2) is implicated in genital neoplasms in horses, including equine penile papillomas, penile intraepithelial neoplasia, and squamous cell carcinoma (SCC). This virus seldom regresses spontaneously and can result in the development of SCC, which may result in significant clinical damage and economic cost. However, the prevalence of this virus is unknown in clinically unaffected horses. The aim of this study was to determine the prevalence of EcPV-2 DNA in genital swabs from healthy horses in the Republic of Korea and to investigate genetic variability within EcPV-2. A total of 797 genital swab samples obtained from Thoroughbred horses (35 stallions and 762 mares) were tested for the presence of the EcPV-2 gene E1 using a polymerase chain reaction (PCR) assay. Positive results were confirmed by repeat PCR to detect the presence of E6 and amplicon sequencing. Equus caballus papillomavirus type 2 DNA was detected in 1% (8/762) of mare swabs but in none of stallion swabs (0/35). All EcPV-2-positive mares had been imported from the United States. Equus caballus papillomavirus type 2 E6 gene sequences were used for phylogenetic analysis and revealed three subdivisions related to the European strains, and three isolates were located on two separate branches. This study documents the molecular prevalence and phylogenetic analysis of EcPV-2 DNA in the Republic of Korea.

Development and validation of a clinical nomogram predicting bladder outlet obstruction via routine clinical parameters in men with refractory nonneurogenic lower urinary tract symptoms.

We aimed to develop and validate a clinical nomogram predicting bladder outlet obstruction (BOO) solely using routine clinical parameters in men with refractory nonneurogenic lower urinary tract symptoms (LUTS). A total of 750 eligible patients ≥50 years of age who had previously not responded (International Prostate Symptom Score [IPSS] improvement <4 points) to at least three different kinds of LUTS medications (including a-blocker) for the last 6 months were evaluated as subcohorts for nomogram development (n = 570) and for split-sample validation (n = 180). BOO was defined as Abrams-Griffiths number ≥40, or 20-39.9 with a slope of linear passive urethral resistance ratio >2 cmH2O ml-1 s-1. A stepwise multivariable logistic regression analysis was conducted to determine the predictors of BOO, and b-coefficients of the final model were selected to create a clinical nomogram. The final multivariable logistic regression model showed that age, IPSS, maximum urinary flow rate, postvoid residual volume, total prostate volume, and transitional zone index were significant for predicting BOO; these candidates were used to develop the final nomogram. The discrimination performance of the nomogram was 88.3% (95% CI: 82.7%-93.0%, P < 0.001), and the nomogram was reasonably well-fitted to the ideal line of the calibration plot. Independent split-sample validation revealed 80.9% (95% CI: 75.5%-84.4%, P < 0.001) accuracy. The proposed BOO nomogram based solely on routine clinical parameters was accurate and validated properly. This nomogram may be useful in determining further treatment, primarily focused on prostatic surgery for BOO, without impeding the detection of possible BOO in men with LUTS that is refractory to empirical medications.

Analysis of factors affecting re-admission after retrograde intrarenal surgery for renal stone.

PURPOSE: To investigate the factors associated with hospital readmission (HR) after retrograde intrarenal surgery (RIRS) among renal stone patients. METHODS: The study included patients who underwent RIRS from June 2011 to December 2017. Patients who were readmitted due to surgery-related complications were evaluated retrospectively. Patient demographics including age, medical comorbidity, body mass indices, ASA score, perioperative parameters and stone factors were compared with total cohorts. HR was defined as visits to the Emergency Room or unplanned admission within 30 days after discharge. The factors affecting HR rates were analyzed using uni- and multi-variate analyses. RESULTS: A total of 572 patients were enrolled into the study. The mean age was 57.6 ± 14.1 years and the mean stone diameter was 13.4 ± 6.2 mm. The mean complication rate was 6.1% and the median hospitalization time was 2.1 ± 3.4 days. HR occurred in 20 patients (3.5%). Compared to non-admission patients, readmitted patients had a higher rate of bilateral RIRS (20.0% vs 12.2%, p = 0.035), number of stones (4.65 vs 2.2, p = 0.041) and higher stone complexity score (4.15 vs 2.11, p = 0.003). Multivariate analysis showed bilateral RIRS (OR 1.091, p = 0.031) and stone complexity (OR 1.405, p = 0.003) were significant factors to predict re-admission after RIRS. CONCLUSION: Patients with complex renal stones or those who underwent bilateral RIRS were more likely to have a higher rate of re-admission. Proper perioperative management to prevent complications should be planned based on these predictive factors.

Secondary inappropriate polycythemia with splenic hemangiosarcoma in a young adult cat.

A 20-month-old castrated male Korean shorthair cat was presented with a 3-week history of intermittent vomiting and anorexia, absolute erythrocytosis, and elevated erythropoietin levels. A diagnosis of splenic hemangiosarcoma was made by histopathology and immunohistochemical identification of factor VIII. Paraneoplastic erythrocytosis caused by a splenic hemangiosarcoma in a cat is described.

Polycythémie secondaire inappropriée et hémangiosarcome splénique chez un jeune chat adulte. Un chat commun coréen mâle castré âgé de 20 mois a été présenté avec une anamnèse de 3 semaines de vomissements intermittents et d'anorexie, d'érythrocytose absolue et des taux élevés d'érythropoïétine. Un diagnostic d'hémangiosarcome splénique a été posé par histopathologie et l'identification immunochimique du facteur VIII. L'érythrocytose paranéoplastique causée par un hémangiosarcorme splénique chez un chat est décrite.(Traduit par Isabelle Vallières).

Accurate Risk Assessment of Patients with Pathologic T3aN0M0 Renal Cell Carcinoma.

To develop a more precise risk-stratification system by investigating the prognostic impact of tumor growth within fatty tissues surrounding the kidney and/or renal vein. We conducted a retrospective review of the medical records of 211 patients with a pathologic diagnosis of T3aN0M0RCC among 4,483 renal cell carcinoma (RCC) patients from February 1988 to December 2015 according to the number of T3a pathologies-extrarenal fat invasion (EFI) and/or renal venous invasion (RVI). During a mean follow-up duration of 38.8 months, the patients with both pathologies (EFI + RVI) had lower recurrence free survival (RFS) rate than those with only a single pathology (p = 0.001). Using multivariable Cox regression analysis, the presence of both factors was shown to be an independent predictor of RFS (HR = 1.964, p = 0.032); cancer specific survival rate was not different among patients with EFI and/or RVI. Patients with pathologic T3aN0M0 RCC presenting with both EFI and RVI were at an increased risk of recurrence following nephrectomy. Therefore, pathologic T3a RCC could be sub-divided into those with favorable and unfavorable disease according to presence of EFI and/or RVI pathologies.

Detection of Felis catus papillomavirus type 2 within multicentric basosquamous carcinoma in a domestic cat.

A 12-year-old neutered male domestic shorthair cat was presented with a 3-year history of multiple nonpruritic, ulcerated, plaque-like skin lesions but no other clinical signs. A systemic examination revealed mild lymphadenopathy. Histopathologic analysis of the skin lesions revealed multicentric basosquamous carcinoma (BSC). Immunohistochemical analysis, PCR, and sequencing detected Felis catus papillomavirus type 2 (FcaPV-2) within the tumors. As BSC is rare in cats, clinical behavior has not been established. To our knowledge, this is the first case report to demonstrate detection of FcaPV-2 within a BSC in a domestic cat.

Rapid Soft Tissue Approximation and Repair using Laser-activated Silk Nanosealants.

Tissue approximation and repair have been conventionally performed with sutures and staples, but these means are inherently traumatic. Tissue approximation using laser-responsive nanomaterials can lead to rapid tissue sealing and repair, and is an attractive alternative to existing clinical methods. Here, we demonstrate the use of laser-activated nanosealants (LANS) with gold nanorods (GNRs) embedded in silk fibroin polypeptide matrices. The adaptability of LANS for sealing soft tissues is demonstrated using two different modalities: insoluble thin films for internal, intestinal tissue repair, and semi-soluble pastes for external repair, shown by skin repair in live mice. Laser repaired intestinal tissue held over seven times more fluid pressure than sutured intestine and also prevented bacterial leakage. Skin incisions in mice closed using LANS' showed indication of increased mechanical strength and faster repair compared to suturing. Laser-activated silk-GNR nanosealants rapidly seal soft-tissue tears and show high promise for tissue approximation and repair in trauma and routine surgery.

Intraprostatic locations of tumor foci of higher grade missed by diagnostic prostate biopsy among potential candidates for active surveillance.

To establish optimal biopsy scheme for selection of candidates for active surveillance (AS) among prostate cancer (PCa) patients, information on topographical distribution of tumor foci of higher grade missed by contemporary biopsy amongst potential candidates of AS would certainly be useful. Thus we analyzed topographic distribution of tumor foci by examining prostatectomy specimens in 444 patients who underwent radical prostatectomy for low risk PCa. Anterior and posterior prostate areas were demarcated by a horizontal line drawn at midpoint of prostatic urethra. Among 444 subjects, patients with upgrading showed relatively higher prevalence of index tumor foci in anterior prostate than those without upgrading, though not reaching statistical significance (p = 0.252). Meanwhile, among 135 (30.4%) patients with very low risk PCa, patients with upgrading showed significantly higher prevalence of index tumor foci in anterior prostate than those without upgrading (52.2% vs 33.8%; p = 0.031). In conclusions, tumor foci of higher grade missed by diagnostic biopsy were mostly located in anterior prostate among very low risk PCa patients. Such finding would be concrete evidence to support the notion that more efforts are needed to increase accuracy in detecting tumor foci in anterior prostate among potential candidates for AS.

Clinical importance of the antibiotic regimen in transrectal ultrasound-guided biopsy: quinolone versus cephalosporin.

BACKGROUND: Quinolone is recommended as an antimicrobial prophylaxis to prevent infectious complication after transrectal ultrasound-guided biopsy, but the increased appearance of quinolone-resistant organism has raised concerns about the efficacy of quinolone. The current study was performed to evaluate various clinical factors including antimicrobial regimens associated with infectious complication after transrectal ultrasound-guided prostate biopsy. METHODS: The medical records of 5215 patients who underwent a multicore transrectal ultrasound-guided prostate biopsy between May 2003 and January 2013 at our institution were reviewed. We analyzed clinical variables including prostate-specific antigen, International Prostate Symptom Score, antimicrobial regimen, prostate size, and number of biopsy cores. Univariate and multivariate logistic regression analyses of infection-related hospitalization after prostate biopsy were performed. RESULTS: The mean age and median prostate-specific antigen of the entire cohort were 66 years and 6.4 ng/ml, respectively. Twenty-eight (0.54 %) patients developed an infectious complication after prostate biopsy that required hospitalization. Patients who received prophylactic quinolone showed a higher infectious hospitalization rate than patients who received prophylactic third-generation cephalosporin (1.5 vs. 0.3 %; p < 0.001). Multivariate logistic regression analysis demonstrated that the International Prostate Symptom Score (odds ratio = 3.18, 95 % confidence interval 1.24-8.13, p = 0.016) and the use of third-generation cephalosporin (odds ratio = 0.21, 95 % confidence interval 0.10-0.44, p < 0.001) were independent predictors of infection-related hospitalization after prostate biopsy. CONCLUSION: With the emergence of quinolone-resistant microorganisms, third-generation cephalosporin may effectively reduce the risk of infectious complications after transrectal ultrasound-guided prostate biopsy. Severe lower urinary tract symptoms may also be an independent risk factor for infection-related hospitalization after transrectal ultrasound-guided prostate biopsy.

Anatomical factors affecting the time required for microsurgical subinguinal varicocelectomy.

BACKGROUND: Microsurgical subinguinal varicocelectomy (MSV) is considered an effective and less morbid procedure, but the difficulty in preserving testicular arteries is a limitation of this procedure. We identified the microanatomy encountered during MSV and clarify its significance to the difficulty of the procedure. METHODS: Three hundred and twenty-six patients who underwent left MSV were evaluated. Detailed intraoperative microanatomy was recorded for each case. A classification system was used to assess the anatomical relationship between the internal spermatic artery and the varicose veins as follows: type I (non-adherent to the veins), type II (adherent to the veins), and type III (surrounded by veins). Type III cases were further divided into types III-a (an arterial pulse) and III-b (a blurred arterial pulse). A linear regression analysis of the factors associated with the length of the operation was used to determine the difficulty of the surgery. RESULTS: A mean number of 8.2 internal spermatic veins were ligated. Internal spermatic arteries were classified as type I in 14 % of patients, type II in 57 %, and type III in 29 % (III-a in 20 % and III-b in 9 %). A large number of internal spermatic veins and higher internal spermatic artery type were observed significantly more often in grade 3 varicoceles (p < 0.05). The types of internal spermatic arteries (ρ = 0.458) and numbers of internal spermatic veins (ρ = 0.431), cremasteric veins (ρ = 0.197), and gubernacular veins (ρ = 0.119) were significantly associated with the length of the operation (p < 0.05). CONCLUSIONS: Anatomical factors were associated with the varicocele grade and surgical difficulty. These findings are helpful to perform MSV.

Comparison of the Width of Peritumoral Surgical Margin in Open and Robotic Partial Nephrectomy: A Propensity Score Matched Analysis.

BACKGROUND: To compare the surgical margin status after open partial nephrectomy (OPN) and robotic partial nephrectomy (RPN) performed in patients with T1a renal cell carcinoma (RCC). METHODS: This was a propensity score-matched study including 702 patients with cT1a RCC treated with partial nephrectomy (PN) between May 2003 and July 2015. Perioperative parameters, including surgical margin width after PN, were compared between two surgical methods. After determining propensity score for tumor size and location, the width of peritumoral surgical margin was investigated. Multivariate logistic analysis to predict peritumoral surgical margin less than 1mm was analyzed. RESULTS: The mean width of peritumoral surgical margin was 2.61 ± 2.15 mm in OPN group (n = 385), significantly wider than the 2.29 ± 2.00 mm of RPN group (n = 317) (p = 0.042). The multivariate analysis showed surgical methods was significant factors to narrow surgical margin less than 1mm (p = 0.031). After propensity score matching, the surgical margin width was significantly longer in OPN (2.67 ± 2.14 mm) group than RPN (2.25 ± 2.03 mm) group (p = 0.016). A positive resection margin occurred in 7 (1.8%) patients in the OPN group and 4 (1.3%) in the RPN group. During the median follow-up of 48.3 months, two patients who underwent OPN had tumor bed recurrence. CONCLUSIONS: RPN may result in a narrower peritumoral surgical margin than OPN. Further investigation on the potential impact of such a phenomenon should be performed in a larger-scale study.

Phosphodiesterase Type 5 Inhibitor Use Following Radical Prostatectomy is not Associated with an Increased Risk of Biochemical Recurrence.

OBJECTIVE: Recently, conflicting findings have been reported on the effect of phosphodiesterase type 5 inhibitor (PDE5I) use on biochemical outcome following radical prostatectomy (RP). Thus, we investigated the impact of PDE5I treatment following RP, including therapeutic strategy, timing, duration, and drug type, on oncologic outcomes. METHODS: We analyzed records of 1082 patients who underwent bilateral nerve-sparing RP for clinically localized prostate cancer (PCa) between 2005 and 2014. Patients were categorized according to PDE5I use within 2 years following RP: non-user, on-demand, and rehabilitation (daily PDE5I use for ≥3 months) groups. Associations of various factors with biochemical recurrence (BCR) were analyzed using a Cox multivariate proportional hazards model. Propensity score-matched analysis was also performed. RESULTS: Among the subjects included in our study, PDE5I use was as follows: 253 (23.4 %) non-users, 475 (43.9 %) on-demand users, and 354 (32.7 %) in the rehabilitation. Multivariate analysis showed that PDE5I use was not a significant factor with regard to BCR risk [hazard ratio 1.47 (0.765-2.826); p = 0.248). Among the PDE5I users, a strategy for PDE5I use (on-demand vs. rehabilitation), timing of initiating PDE5I treatment following RP, duration of PDE5I use, and type of PDE5I used were not associated with an increased BCR risk in multivariate analyses (p = 0.304, p = 0.177, p = 0.332, and p = 0.105, respectively). In addition, PDE5I use was not associated with an increased risk of BCR among 478 matched cohorts (p = 0.672). CONCLUSIONS: PDE5I treatment following RP was not found to have any significant impact on biochemical outcome regardless of therapeutic strategy, timing, duration, and drug type. Such findings suggest that PDE5I treatment following RP is oncologically safe.

Risk of metastasis for T1a renal cell carcinoma.

INTRODUCTION: While active surveillance for small renal mass is gaining acceptance, controversy still continues on true metastatic potential of small renal cell carcinoma (RCC). Thus, we investigated the risks of synchronous/metachronous metastases and their potential predictors among T1a RCC patients who underwent surgical treatment. METHODS: We reviewed data from 2114 patients who received radical or partial nephrectomy for small renal tumor (≤ 4 cm) from 1990 to 2013. For our study, patients were stratified into four different groups according to tumor size (group 1: 0-1.0 cm, group 2: 1.1-2.0 cm, group 3: 2.1-3.0 cm, group 4: 3.1-4.0 cm). Univariate and multivariate analyses were performed to analyze metastatic potentials according to tumor size and identify useful predictors of metastases. RESULTS: Among 1913 T1a RCC patients, there were low but nonnegligible rates of metastases (group 2: 1.1 %, group 3: 3.3 %, group 4: 6.0 %, respectively). Kaplan-Meier analysis showed significant differences in metastasis-free survivals between groups (p < 0.001). A linear positive association was observed between tumor size and metastatic rate (p < 0.001). Diabetic T1a RCC patients showed significantly inferior metastasis-free survival than nondiabetic counterparts (p = 0.003). Multivariate analysis revealed that tumor size and history of diabetes mellitus were independently associated with metastasis in T1a RCC. CONCLUSIONS: As T1a RCCs present low but nonnegligible risk of metastasis, patients with small renal mass should be counseled on such risk when offered active surveillance. Larger tumor size and history of diabetes mellitus may be associated with higher risk of metastasis in T1a RCC.