Merkel cell carcinoma. Report of one caseMerkel cell carcinoma is a rare neuroendocrine tumor typically found on sun-exposed areas such as face and extremities. We report a 57 years old male presenting with a tumor in the left perianal region that prior to surgery was catalogued as a perianal teratoma. The pathological study informed a Merkel cell tumor. It was locally excised and a cutaneous flap was made. Two years after surgery, the patient had pulmonary metastases and chemotherapy was started. Due to lack of response, it was discontinued after four cycles.Key words: Merkel cell tumor, local excision, pulmonary metastases. ResumenLos tumores de células de Merkel, son raros tumores neuroendocrinos que típicamente son encontrados en zonas expuestas al sol como cara y extremidades. Describimos un caso de un paciente de 57 años de edad con una tumoración en la región perianal que inicialmente se catalogó como un teratoma, cuya histopatología informó un tumor de células de Merkel. Se manejo con resección local amplia y colgajo cutáneo. Después de 2 años de la cirugía, el paciente evolucionó con claros signos de enfermedad metastásica pulmonar y actualmente se encuentra en manejo paliativo con quimioterapia.Palabras clave: Tumor de células de Merkel, resección local, enfermedad metastásica. IntroducciónEl carcinoma de células de Merkel o carcinoma neuroendocrino cutáneo es un tumor poco frecuente y agresivo, asociado a una elevada tendencia a invasión ganglionar, recurrencia y metástasis a distancia. La etiología de éste, así como en muchos de los tumores cutáneos descritos, es desconocida. La hipótesis más aceptada es aquella que describe el efecto oncogénico de las radiaciones solares aso- CASOS CLÍNICOS

Single port transanal excision for local treatment of rectal lesionsBackground: Since 2009, transanal minimally invasive surgery (TAMIS) is increasingly used as an alternative to local excision and transanal microscopic excision (TEM) for rectal lesions located in the mid and superior third. The clinical benefits of the technique are being evaluated. Aim: To establish the feasibility, quality of excision and short term results of single port transanal excision for rectal lesions. Patients and Methods: Analysis of a prospective series of patients subjected to single port transanal excision. Patients had benign or malignant lesions located in the mid or superior third of the rectum. Those with a diagnosis of adenocarcinoma were excluded. Results: The transanal resection using the SILS Port ® was completed in 11 patients aged 21 to 86 years (eight women). The American Society of Anesthesiologists (ASA) classification of patients was two and their body mass index was 24 ± 3.1 kg/m 2 . The lesion distance from the anal margin ranged from 5 to 10 cm. The surgical time was 47 min and hospital stay was 2.8 days. One patient was converted to conventional transanal surgery and two patients had self-limited episode of hematochezia. Conclusions: TAMIS is a feasible technique and with promising results in selected patients.

Artificial bowel sphincter for anorectal reconstruction. Preliminary report and review of surgical technique Introduction: The artificial sphincter (ABS) has been proposed as an option for the treatment for severe refractory fecal incontinence. We have witnessed a great discussion on systematic reviews regarding the short-and long-term results of ABS, assessing its real benefit. Objective: To analyze the surgical outcomes of patients undergoing artificial sphincter implantation and review of surgical technique. Material and Methods: Between 2003 and 2007, the ABS system was introduced in four patients. The mean age was 34 years (13 to 54 years). Two patients were admitted for rectal agenesis, a severe anorectal trauma and abdominoperineal resection for a low rectal cancer. Results: Follow-up time was 12 to 60 months. We performed the explantation of the device for perineal wound infection in one case. All patients had mild incontinence ABS showed a decrease an average of 3.5 points to 12 months of follow-up on the Wexner Scale. Conclusions: The installation of the artificial sphincter is a feasible and safe alternative for anorectal reconstruction in selected patients. The morbidity and explantation of the series is similar to other international reports.

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Bowel obstruction caused by an omphalomesenteric duct remnant. Report of one caseOmphalomesenteric duct remnant is one of the least common congenital abnormalities due to vitelline sac persistence. Among the five types of this abnormalities, omphalomesenteric band or obliterated omphalomesenteric duct remnant is the least common. We report a 64 years old male presenting with vomiting, abdominal pain and absence of stools. The patient was operated with the diagnosis of intestinal obstruction and a persistent omphalomesenteric duct that caused the bowel obstruction was found. The patient had an uneventful postoperative period as is discharged 24 hours later.Key words: Omphalomesenteric duct, bowel obstruction, vitelline sac. ResumenEl remanente del conducto onfalomesentérico es una de las anomalías congénitas más raras asociadas con la permanencia del saco vitelino. Dentro de los cinco subtipos que se describen en la literatura, la banda onfalomesentérica o conducto onfalomesentérico obliterado es el de menor frecuencia. Presentamos un caso muy infrecuente de persistencia del conducto onfalomesentérico, que ocasionó una obstrucción intestinal en un paciente adulto y que fue resuelto de forma quirúrgica.Palabras clave: Conducto onfalomesentérico, obstrucción intestinal, saco vitelino. IntroducciónLa obstrucción intestinal de intestino delgado es una emergencia quirúrgica común y encontrada frecuentemente en laparotomías exploradoras. Es una causa importante de morbilidad y mortalidad en hospitales alrededor del mundo. El remanante del conducto onfalomesentérico es una de las anomalías congénitas más raras asociadas con la permanencia del saco vitelino 1 . Este remanante puede oca- CASOS CLÍNICOS