Adaptive sequence evolution in a color gene involved in the formation of the characteristic egg-dummies of male haplochromine cichlid fishes

Background  

The exceptionally diverse species flocks of cichlid fishes in East Africa are prime examples of parallel adaptive radiations. About 80% of East Africa's more than 1 800 endemic cichlid species, and all species of the flocks of Lakes Victoria and Malawi, belong to a particularly rapidly evolving lineage, the haplochromines. One characteristic feature of the haplochromines is their possession of egg-dummies on the males' anal fins. These egg-spots mimic real eggs and play an important role in the mating system of these maternal mouthbrooding fish.     

Prevention of Anal Condyloma with Quadrivalent Human Papillomavirus Vaccination of Older Men Who Have Sex with Men

Background

The quadrivalent human papillomavirus vaccine (qHPV) is FDA-approved for use in males 9 to 26 years old to prevent anogenital condyloma. The objective of this study is to determine if qHPV is effective at preventing anal condyloma among men who have sex with men (MSM) aged 26 years and older.

Methods

This post-hoc analysis of a nonconcurrent cohort study evaluated 210 patients without history of anal condyloma and 103 patients with previously-treated anal condyloma recurrence-free for at least 12 months prior to vaccination/time zero. We determined the rate of anal condyloma development in vaccinated versus unvaccinated patients.

Results

313 patients with mean age 42 years were followed for median 981 days. During 773.6 person-years follow-up, condyloma developed in 10 (8.6%) vaccinated patients (incidence of 3.7 per 100 person-years) and 37 (18.8%) unvaccinated patients (incidence 7.3 per 100 person-years; p = 0.05). Multivariable hazards ratio showed that qHPV was associated with decreased risk of anal condyloma development (HR 0.45; 95% CI 0.22–0.92; p = 0.03). History of anal condyloma was associated with increased risk of anal condyloma development (HR 2.28; 95% CI 1.28–4.05; p = 0.005), as was infection with oncogenic HPV (HR 3.87; 95% CI 1.66–9.03; p = 0.002).

Conclusions

Among MSM 26 years of age and older with and without history of anal condyloma, qHPV reduces the risk of anal condyloma development. A randomized controlled trial is needed to confirm these findings in this age group.     

Anorectal Chlamydia trachomatis Load Is Similar in Men Who Have Sex with Men and Women Reporting Anal Sex

Background

Anorectal Chlamydia trachomatis (chlamydia) is frequently diagnosed in men who have sex with men (MSM) and in women, but it is unknown whether these infections are comparable in clinical impact and transmission potential. Quantifying bacterial load and identifying determinants associated with high bacterial load could provide more insight.

Methods

We selected a convenience sample of MSM who reported anal sex (n = 90) and women with concurrent urogenital/anorectal chlamydia who reported anal sex (n = 51) or did not report anal sex (n = 61) from the South Limburg Public Health Service’s STI unit. Bacterial load (Chlamydia/ml) was quantified for all samples and log transformed for analyses. Samples with an unquantifiable human leukocyte antigen (n = 9) were excluded from analyses, as they were deemed inadequately sampled.

Results

The mean log anorectal chlamydia load (3.50) was similar for MSM and women who reported having anal sex (3.80, P = 0.21). The anorectal chlamydia load was significantly higher in these groups than in women who did not report having anal sex (2.76, P = 0.001). Detectable load values ranged from 1.81–6.32 chlamydia/ml for MSM, 1.74–7.33 chlamydia/ml for women who reported having anal sex and 1.84–6.31 chlamydia/ml for women who did not report having anal sex. Symptoms and several other determinants were not associated with anorectal chlamydia load.

Conclusions

Women who did not report anal sex had lower anorectal loads, but they were within a similar range to the other two groups. Anorectal chlamydia load was comparable between MSM and women who reported anal sex, suggesting similar transmission potential.     

Non-rigid registration of a 3D ultrasound and a MR image data set of the female pelvic floor using a biomechanical model

Background  

The visual combination of different modalities is essential for many medical imaging applications in the field of Computer-Assisted medical Diagnosis (CAD) to enhance the clinical information content. Clinically, incontinence is a diagnosis with high clinical prevalence and morbidity rate. The search for a method to identify risk patients and to control the success of operations is still a challenging task. The conjunction of magnetic resonance (MR) and 3D ultrasound (US) image data sets could lead to a new clinical visual representation of the morphology as we show with corresponding data sets of the female anal canal with this paper.     

Anal HPV infection in HIV-positive men who have sex with men from China

Background

Anal HPV infection, which contributes to the development of anal warts and anal cancer, is well known to be common among men who have sex with men (MSM), especially among those HIV positives. However, HIV and anal HPV co-infection among MSM has not been addressed in China.

Methods

A cross-sectional study was conducted in Beijing and Tianjin, China. Study participants were recruited using multiple methods with the collaboration of local volunteer organizations. Blood and anal swabs were collected for HIV-1 serological test and HPV genotyping.

Results

A total of 602 MSM were recruited and laboratory data were available for 578 of them (96.0%). HIV and anal HPV prevalence were 8.5% and 62.1%, respectively. And 48 MSM (8.3%) were found to be co-infected. The HPV genotypes identified most frequently were HPV06 (19.6%), HPV16 (13.0%), HPV52 (8.5%) and HPV11 (7.6%). Different modes of HPV genotypes distribution were observed with respect to HIV status. A strong dose-response relationship was found between HIV seropositivity and multiplicity of HPV genotypes (p<0.001), which is consistent with the observation that anal HPV infection was an independent predictor for HIV infection.

Conclusions

A high prevalence of HIV and anal HPV co-infection was observed in the MSM community in Beijing and Tianjin, China. Anal HPV infection was found to be independently associated with increased HIV seropositivity, which suggests the application of HPV vaccine might be a potential strategy to reduce the acquisition of HIV infection though controlling the prevalence of HPV.     

HPV Infections among MSM in Shenzhen,China

Background

An increasing incidence of anal cancer among men, especially men who have sex with men (MSM) suggests a need to better understand anal human papillomavirus (HPV) infection among this group.

Methods

A cross-sectional study was conducted among MSM in Shenzhen, China. Blood was collected for HIV serological testing and syphilis serological screening, and anal swabs were collected for HPV genotyping. Difference of HPV prevalence between HIV seropositive and HIV seronegative MSM was assessed by chi-square test. Factors associated with anal canal HPV infection were assessed by univariate and multivariate logistic regression.

Results

A total of 408 MSM were recruited. HIV and HPV prevalence were 6.9% and 36.4%, respectively. HPV was detected in the anal canal in 71.4% of the HIV-positive MSM and in 33.8% of the HIV-negative MSM (P<0.001). Oncogenic types were seen more often in anal specimens of HIV-positive MSM than in specimens of HIV-negative MSM (P = 0.001). The HPV genotypes detected most frequently were HPV06 (8.2%), HPV16 (7.2%), HPV11 (6.4%), HPV18 (4.7%), HPV58 (4.7%), and HPV52 (4.2%).

Conclusions

In this study, HIV positive MSM had a higher burden of HPV infection, especially oncogenic HPV infection. HPV types 52 and 58 were as popular as those types designed for the currently available vaccine (HPV6, 11, 16, 18).     

Comparative accuracy of anal and cervical cytology in screening for moderate to severe dysplasia by magnification guided punch biopsy: a meta-analysis

Background

The accuracy of screening for anal cancer precursors relative to screening for cervical cancer precursors has not been systematically examined. The aim of the current meta-analysis was to compare the relative accuracy of anal cytology to cervical cytology in discriminating between histopathologic high grade and lesser grades of dysplasia when the reference standard biopsy is obtained using colposcope magnification.

Methods and Findings

The outcome metric of discrimination was the receiver operating characteristic (ROC) curve area. Random effects meta-analysis of eligible studies was performed with examination of sources of heterogeneity that included QUADAS criteria and selected covariates, in meta-regression models. Thirty three cervical and eleven anal screening studies were found to be eligible. The primary meta-analytic comparison suggested that anal cytologic screening is somewhat less discriminating than cervical cytologic screening (ROC area [95% confidence interval (C.I.)]: 0.834 [0.809–0.859] vs. 0.700 [0.664–0.735] for cervical and anal screening, respectively). This finding was robust when examined in meta-regression models of covariates differentially distributed by screening setting (anal, cervical).

Conclusions

Anal cytologic screening is somewhat less discriminating than cervical cytologic screening. Heterogeneity of estimates within each screening setting suggests that other factors influence estimates of screening accuracy. Among these are sampling and interpretation errors involving both cytology and biopsy as well as operator skill and experience.     

Association of human papillomavirus infection and abnormal anal cytology among HIV-infected MSM in Beijing, China

Background

In the recent years, dramatic increases in HIV transmission among men who have sex with men (MSM) have been observed in China. Human papillomavirus (HPV) infection related anal cancer is more common among HIV-infected MSM as compared to the general population. However, HPV infection and anal cytology has been rarely studied in HIV-infected MSM in China.

Methods

HIV-infected MSM in Beijing, China were invited to participate in this study between January and April 2011. Anal swabs were collected for examining cytology and HPV genotypes.

Results

Ninety-five eligible participants with complete questionnaire and laboratory data were included in the analyses. Thirty six of them (37.9%) showed abnormal anal cytology as follows: atypical squamous cells of undetermined significance (ASC-US) in 19 (20.0%), atypical squamous cells but cannot exclude HSIL (ASC-H) in 1 (1.1%), low-grade squamous intraepithelial lesion (LSIL) in 15 (15.8%), and high-grade squamous intraepithelial lesion (HSIL) in 1 (1.1%). HPV6 (20.0%), HPV16 (10.9%), HPV56 (10.9%), HPV52 (9.1%) and HPV39 (9.1%) were observed most frequently among those with normal anal cytology, while different distribution was found in the ones with abnormal anal cytology as HPV6 (19.4%), HPV16 (19.4%), HPV45 (16.7%), HPV52 (16.7%) and HPV18 (11.1%). In addition, HPV16, HPV45, HPV52 and HPV18 were the most frequent high-risk types in patients with abnormal anal cytology. HPV multiplicity was found to be significantly related to the prevalence of abnormal anal cytology (p for trend = 0.04).

Conclusions

High prevalence of HPV infection and abnormal anal cytology was observed among HIV-infected MSM in China. Infection of multiple HPV types or high-risk types was found to be associated with an increased risk of abnormal anal cytology.     

Risk Factors for the Presence of Anal Intraepithelial Neoplasia in HIV+ Men Who Have Sex with Men

Objective

Anal Intraepithelial Neoplasia (AIN) is present in the majority of HIV+ men who have sex with men (MSM) and routine AIN-screening is subject of discussion. In this study we analysed a wide range of potential risk factors for AIN in order to target screening programs.

Methods

We screened 311 HIV+ MSM by high resolution anoscopy, with biopsies of suspect lesions. HIV-parameters, previous sexual transmitted infections (STI’s), anal pathology, sexual practices and substance use were analysed in relation to AIN by uni- and multivariable logistic regression.

Results

AIN (any grade) was found in 175/311 MSM (56%), high grade (HG)AIN in 30%. In the univariable analysis, years since HIV diagnosis, years of antiretroviral therapy (cART) and anal XTC use decreased AIN risk, while a history of anogenital warts and use of GHB (γ-hydroxybutyric acid) increased this risk. In the multivariable analysis three parameters remained significant: years of cART (OR=0.92 per year, p=0.003), anal XTC use (OR=0.10, p=0.002) and GHB use (OR=2.60, p=0.003). No parameters were significantly associated with HGAIN, but there was a trend towards increased risk with anal enema use prior to sex (>50 times ever; p=0.07) and with a history of AIN (p=0.06). CD4 count, STI’s, anal pathology, smoking, number of sex partners and anal fisting were not associated with (HG)AIN.

Conclusion

GHB use increases the risk for AIN, while duration of cART and anal XTC use are negatively correlated with AIN. Given the high prevalence of AIN in HIV+ MSM, these associations are not helpful to guide a screening program.     

Epidemiology of Anal HPV Infection in High-Risk Men Attending a Sexually Transmitted Infection Clinic in Puerto Rico

Purpose

Recent studies in Puerto Rico have reported an increasing incidence of anal cancer in Puerto Rican men. The objective of this study was to determine the prevalence, genotype distribution and risk factors associated with anal HPV infection among men attending an STI clinic in Puerto Rico.

Methods

We conducted a cross-sectional study among 205 men 18 years and older. A comprehensive survey was administered that included a demographic and a behavioral assessment. Separate logistic regression models were performed to determine factors associated with any, high-risk (HR), and multiple anal HPV infection.

Results

The mean age of the study sample was 38.0±13.5 years. The most common HR types were 58, 51 and 31. Overall, HR anal HPV infection was found in 53.5% of the participants. Multiple HPV types in the anal canal were found in 47.6% of the sample. A third (29.8%) of participants reported being men who had sex with men (MSM). MSM had a significantly higher prevalence of any, HR and multiple HPV infection (p-value<0.05). Separate multivariate logistic regression analyses showed that being MSM was associated with any (OR = 4.5; [95%CI: 1.9–10.7]), HR (OR = 3.4; [95%CI: 1.1–10.3) and multiple anal HPV infection (OR = 3.6; [95%CI: 1.5–9.1). HIV was marginally associated with multiple anal HPV infection in multivariate analysis (OR = 3.3; 95%CI = 1.0–11.0).

Conclusions

Anal HPV is common among sexually active men attending this STI clinic, with higher likelihood of anal HPV infection among MSM.     

Gastrointestinal stromal tumor of the anal canal: an unusual presentation

Background

Gastrointestinal stromal tumors (GIST) of the stomach are the most frequent followed by those of the intestinal tract, while colon and rectum represent rare sites. GIST of the anal canal are extremely rare. They have been studied along with GIST of the rectum, as a single entity, and along with them they represent 5% of GIST. GIST arising from the anal canal account for only 2%–8% of the anorectal GIST. Thus anal GIST must be considered an exceptional case.

Case presentation

A 78-year-old man was referred to our Institution for an anal mass, in absence of any symptom. The patient was treated by local excision. An histological diagnosis of a low grade GIST was made. No further treatment was necessary. No local recurrence of distant metastases were found at follow-up.

Conclusion

At the moment, only ten cases of c-kit positive anal GIST are reported in the literature. These few data are not sufficient to establish a widely accepted approach for this neoplasia.We recommend to perform an initial local excision, to define the risk of aggressive behavior and the resection margins and proceed to a more aggressive treatment, if the GIST belongs to high or very high risk group. The role of adjuvant therapy is still uncertain. Although inhibitors of tyrosine-kinase receptor needs further studies before their routine use, their role in case of distant or local recurrence has been accepted. Patients' close follow up is mandatory to disclose as soon as possible local recurrences or metastases.

     

A colliding maxillary sinus cancer of adenosquamous carcinoma and small cell neuroendocrine carcinoma - a case report with EGFR copy number analysis

Background

The most common type of carcinoma associated with ulcerative colitis (UC) is adenocarcinoma. We present a case of primary rectal small cell carcinoma in a patient with a history of UC.

Methods

A 34-year-old male diagnosed with UC for 10 years was not consistent with the usual annual follow-up and presented with mucoid-bloody diarrhea. Colonoscopy revealed a rectal mass 2 cm distant from the anal verge. The patient underwent a total proctocolectomy with preservation of the anal sphincters, construction of an ileal reservoir, anastomosis of the reservoir to the anus (J configuration) and protective loop ileostomy.

Results

Histological examination showed undifferentiated small cell carcinoma.

Conclusions

This is the first case of small cell carcinoma in a background of UC reported to be treated surgically and the patient and has no reccurence 18 months postoperatively.     

Relative accuracy of cervical and anal cytology for detection of high grade lesions by colposcope guided biopsy: a cut-point meta-analytic comparison

Background

We recently reported, using a receiver operating characteristic area metric, the first meta-analytic comparison of the relative accuracy of cervical and anal cytology in detecting moderate or severe histopathologic lesions by magnification directed punch biopsy. The aim of the present research was to meta-analytically examine cut-point specific operating characteristics (sensitivity, specificity) of cervical and anal cytology in detecting high grade squamous intraepithelial lesion (HSIL) histopathology by colposcope directed punch biopsy.

Methodology/Principal Findings

The primary eligibility requirement was availability of tabulated cytology (normal, atypical cells of unclear significance [ASCUS], low grade squamous intraepithelial lesion, HSIL or atypical squamous cells cannot rule out high grade [ASC-H]) and biopsy (Conclusions/SignificanceUsing a cytology cut-point of HSIL or ASC-H, anal cytology is less sensitive but comparably specific to cervical cytology. However, using a cut-point of ASCUS, differences in accuracy were of borderline significance.     

HIV Transmission among Men Who Have Sex with Men due to Condom Failure

Background

Despite preventive efforts, HIV incidence remains high among men who have sex with men (MSM) in industrialized countries. Condoms are an important element in prevention but, given the high frequency of condom use and their imperfect effectiveness, a substantial number and proportion of HIV transmissions may occur despite condoms. We developed a model to examine this hypothesis.

Methods

We used estimates of annual prevalent and incident HIV infections for MSM in Ontario. For HIV-negative men, we applied frequencies of sexual episodes and per-contact HIV transmission risks of receptive and insertive anal sex with and without a condom and oral sex without a condom. We factored in the proportion of HIV-infected partners receiving antiretroviral therapy and its impact in reducing transmissibility. We used Monte-Carlo simulation to determine the plausible range for the proportion of HIV transmissions for each sexual practice.

Results

Among Ontario MSM in 2009, an estimated 92,963 HIV-negative men had 1,184,343 episodes of anal sex with a condom and 117,133 anal sex acts without a condom with an HIV-positive partner. Of the 693 new HIV infections, 51% were through anal sex with a condom, 33% anal sex without a condom and 16% oral sex. For anal sex with a condom, the 95% confidence limits were 17% and 77%.

Conclusions

The proportion of HIV infections related to condom failure appears substantial and higher than previously thought. That 51% of transmissions occur despite condom use may be conservative (i.e. low) since we used a relatively high estimate (87.1%) for condom effectiveness. If condom effectiveness were closer to 70%, a value estimated from a recent CDC study, the number and proportion of HIV transmissions occurring despite condom use would be much higher. Therefore, while condom use should continue to be promoted and enhanced, this alone is unlikely to stem the tide of HIV infection among MSM.     

Anal canal plasmacytoma—An uncommon presentation site

Background

Extramedullary plasmacytomas (EMP) are rare plasma cell tumors that arise outside the bone marrow. They are most often located in the head and neck region, but may also occur in the other locations. The lower gastrointestinal EMP represents less than 5% of all cases, and location in the anal canal is exceedingly rare.

Aim

We present an exceedingly rare case of anal canal plasmacytoma, aiming to achieve a better understanding of this rare entity.

Methods

We report a case of a 61-year-old man with a bulky mass in the anal canal. The lesion measured about 6 cm and invaded in all layers of the anal canal wall. The biopsy was performed and revealed a round and plasmocitoid cell population with a solid growth pattern and necrosis. The tumoral cells have express CD79a and CD138 with lambda chains. There was no evidence of disease in other locations and these features were consistent with the diagnosis of an extra-osseous plasmacytoma. The patient was submitted to conformal radiotherapy 50.4 Gy total dose, 1.8 Gy per fraction. After 24 months, the patient is asymptomatic and the lesion has completely disappeared.

Conclusions

EMP accounts for approximately 3% of plasma cell malignancies. The median age is about 60 years, and the majority of patients are male. The treatment of choice for extramedullary plasmacytoma is radiation therapy in a dosage of about 50 Gy. Patients should be followed-up for life with repeated bone marrow aspiration and protein studies to detect the development of multiple myeloma.     

Natural History of Anal Dysplasia in an HIV-Infected Clinical Care Cohort: Estimates Using Multi-State Markov Modeling

Objectives

(1) To model the natural history of anal neoplasia in HIV-infected patients using a 3-state Markov model of anal cancer pathogenesis, adjusting for cytology misclassification; and (2) to estimate the effects of selected time-varying covariates on transition probabilities.

Design

A retrospective cytology-based inception screening cohort of HIV-infected adults was analyzed using a 3-state Markov model of clinical pathogenesis of anal neoplasia.

Methods

Longitudinally ascertained cytology categories were adjusted for misclassification using estimates of cytology accuracy derived from the study cohort. Time-varying covariate effects were estimated as hazard ratios.

Results

(1) There was a moderate to high probability of regression of the high grade squamous intraepithelial lesion (HSIL) state (27–62%) at 2 years after initial cytology screening; (2) the probability of developing invasive anal cancer (IAC) during the first 2 years after a baseline HSIL cytology is low (1.9–2.8%); (3) infrared coagulation (IRC) ablation of HSIL lesions is associated with a 2.2–4.2 fold increased probability of regression to <HSIL; and (4) antiretroviral therapy, suppressed HIV plasma viral load, and CD4 ≥350/mm³ are each associated with reduced probability of progression from <HSIL to HSIL.

Conclusions

The finding of moderate to high rates of regression of the HSIL state accompanied by low rates of progression to IAC should inform both screening and precursor treatment guideline development. There appears to be a consistent and robust beneficial effect of antiretroviral therapy, suppressed viral load, and higher CD4 on the transition from the <HSIL state to the HSIL state.     

Association between Free Testosterone Levels and Anal Human Papillomavirus Types 16/18 Infections in a Cohort of Men Who Have Sex with Men

Background

Human papillomavirus (HPV) types 16 and 18 cause invasive cervical cancer and most invasive anal cancers (IACs). Overall, IAC rates are highest among men who have sex with men (MSM), especially MSM with HIV infection. Testosterone is prescribed for men showing hypogonadism and HIV-related wasting. While there are direct and indirect physiological effects of testosterone in males, its role in anal HPV16/18 infections in men is unknown.

Methods

Free testosterone (FT) was measured in serum from 340 Multicenter AIDS Cohort Study (MACS) participants who were tested for anal HPV16/18-DNA approximately 36 months later. The effect of log10-transformed current FT level on anal HPV16/18 prevalence was modeled using Poisson regression with robust error variance. Multivariate models controlled for other HPV types, cumulative years of exogenous testosterone use, race, age, lifetime number of receptive anal intercourse partnerships, body mass index, tobacco smoking, HIV-infection and CD4+ T-cell counts among HIV-infected, and blood draw timing.

Results

Participants were, on average, 60 (+5.4) years of age, White (86%), and HIV-uninfected (56%); Twenty-four percent tested positive for anal HPV16 and/or 18-DNA (HPV16 prevalence=17.1%, HPV18=9.1%). In adjusted analysis, each half-log10 increase of FT was associated with a 1.9-fold (95% Confidence Interval: 1.11, 3.24) higher HPV16/18 prevalence. Additionally, other Group 1 high-risk HPVs were associated with a 1.56-fold (1.03, 2.37) higher HPV16/18 prevalence. Traditional risk factors for HPV16/18 infection (age, tobacco smoking; lifetime number of sexual partners, including the number of receptive anal intercourse partnerships within 24 months preceding HPV testing) were poorly correlated with one another and not statistically significantly associated with higher prevalence of HPV16/18 infection in unadjusted and adjusted analyses.

Conclusions

Higher free testosterone was associated with increased HPV16/18 prevalence measured approximately three years later, independent of sexual behavior and other potential confounders. The mechanisms underlying this association remain unclear and warrant further study.     

A Novel Pre-Clinical Murine Model to Study the Life Cycle and Progression of Cervical and Anal Papillomavirus Infections

Background

Papillomavirus disease and associated cancers remain a significant health burden in much of the world. The current protective vaccines, Gardasil and Cervarix, are expensive and not readily available to the underprivileged. In addition, the vaccines have not gained wide acceptance in the United States nor do they provide therapeutic value. Papillomaviruses are strictly species specific and thus human viruses cannot be studied in an animal host. An appropriate model for mucosal disease has long been sought. We chose to investigate whether the newly discovered mouse papillomavirus, MmuPV1, could infect mucosal tissues in Foxn1^nu/Foxn1^nu mice.

Methods

The vaginal and anal canals of Foxn1^nu/Foxn1^nu mice were gently abraded using Nonoxynol-9 and “Doctor’s BrushPicks” and MmuPV1 was delivered into the vaginal tract or the anal canal.

Results

Productive vaginal, cervical and anal infections developed in all mice. Vaginal/cervical infections could be monitored by vaginal lavage. Dysplasias were evident in all animals.

Conclusions

Anogenital tissues of a common laboratory mouse can be infected with a papillomavirus unique to that animal. This observation will pave the way for fundamental virological and immunological studies that have been challenging to carry out heretofore due to lack of a suitable model system.     

Acute motor axonal neuropathy associated with anal carcinoma: Paraneoplastic neurological syndrome or coincidence?

Aim

Assessment of the association of an acute motor axonal neuropathy with a squamous cell anal carcinoma.

Background

Paraneoplastic neurologic syndromes are not a direct consequence of neither primary tumor nor its metastasis. They often parallel the course of the malignancy but may be the presenting sign of an occult cancer. Sometimes it is very difficult to distinguish if it is a paraneoplastic syndrome or just a coincidence.

Materials and methods

We report a 60-year-old man that presented with an acute motor deficit of the four limbs. Clinical examination found a pure and severe motor deficit in the four limbs. No sensory abnormality was found and all motor nerves were unexcitable. Electromyography suggested the diagnosis of acute motor axonal neuropathy (AMAN). Four months after developing the AMAN, blood in the stool revealed anal carcinoma. The patient was treated with concurrent chemoradiotherapy. Radiation was given to the tumor and to the pelvis, including inguinal nodes, over a five-week period plus fluorouracil and mitomycin. We investigated the presence of antiganglioside antibodies as studies suggest that carcinomas can express antigens shared with Schwann cells.

Results

Anti-GM1 IgG antibodies were detected by an enzyme-linked immunosorbent assay method. Other antibodies, including antinuclear nucleoprotein antibody (anti-Hu), anti-Tr, anti-Ri, anti-CV2, anti-amphiphysin and anti-Yo, were negative. Clinical improvement of the motor state was observed at the fourth week of oncologic treatment.

Conclusion

The presence of anti-GM1 IgG antibodies and the clinical improvement of the motor state after concurrent chemoradiotherapy lead us to believe there is an association between anal carcinoma and this severe impairment.