Retrorectal Tumors: A Comprehensive Literature Review.

IMPORTANCE: Retrorectal tumors are rare lesions that comprise a multitude of histologic types. Reports are limited to small single-institution case series, and recommendations on the ideal surgical approaches are lacking. OBJECTIVE: The purpose of the study was to provide a comprehensive review of the epidemiology, pathologic subtypes, surgical approaches, and clinical outcomes of retrorectal tumors. EVIDENCE REVIEW: We conducted a review of the literature using PubMed and searched the reference lists of published studies. RESULTS: A total of 341 studies comprising 1708 patients were included. Overall, 68 % of patients were female. The mean age was 44.6 ± 13.7 years. Of all patients, 1194 (70 %) had benign lesions, and 514 patients (30 %) had malignant tumors. Congenital tumors (60.5 %) were the most frequent histologic type. Other pathologic types were neurogenic tumors (14.8 %), osseous tumors (3.1 %), inflammatory tumors (2.6 %), and miscellaneous tumors (19.1 %). Biopsy was performed in 27 % of the patients. Of these patients, incorrect diagnoses occurred in 44 %. An anterior surgical approach (AA) was performed in 299 patients (35 %); a posterior approach (PA) was performed in 443 (52 %), and a combined approach (CA) was performed in 119 patients (14 %). The mean length of stay (LOS) of PA was 7 ± 5 days compared to 8 ± 7 days for AA and 11 ± 7 days for CA (p < 0.05). The overall morbidity rate was 13.2 %: 19.3 % associated with anterior approach, 7.2 % associated with posterior approach, and 24.7 % after a combined approach (p < 0.05). Overall postoperative recurrence rate was 21.6 %; 6.7 % after an anterior approach, 26.6 % after a posterior approach, and 28.6 % after a combined approach (p < 0.05). A minimally invasive approach (MIS) was employed in 83 patients. MIS provided shorter hospital stays than open surgery (4 ± 2 vs. 9 ± 7 days; p < 0.05). Differences in complication rate were 19.8 % in MIS and 12.2 % in open surgery and not statistically significant. CONCLUSIONS AND RELEVANCE: Retrorectal tumors are most commonly benign in etiology, of a congenital nature, and have a female predominance. Complete surgical resection is the cornerstone of retrorectal tumor management. A minimal access surgery approach, when feasible, appears to be a safe option for the management of retrorectal tumors, with shorter operative time and length of stay.

Evaluation of AAV-mediated expression of Chop2-GFP in the marmoset retina.

PURPOSE: Converting inner retinal neurons to photosensitive cells by expressing channelrhodopsin-2 (ChR2) offers a novel approach for treating blindness caused by retinal degenerative diseases. In the present study, the recombinant adeno-associated virus serotype 2 (rAAV2)-mediated expression and function of a fusion construct of channelopsin-2 (Chop2) and green fluorescent protein (GFP) (Chop2-GFP) were evaluated in the inner retinal neurons in the common marmoset Callithrix jacchus. METHODS: rAAV2 vectors carrying ubiquitous promoters were injected into the vitreous chamber. Expression of Chop2-GFP and functional properties of ChR2 were examined by immunocytochemical and electrophysiological methods 3 months after injection. RESULTS: The percentage of Chop2-GFP-expressing cells in the ganglion cell layer was found to be retinal region- and animal age-dependent. The highest percentage was observed in the far-peripheral region. Chop2-GFP expression was also found in the foveal and parafoveal region. In the peripheral retina in young animals with high viral concentrations, the expression of Chop2-GFP was observed in all major classes of retinal neurons, including all major types of ganglion cells. The morphologic properties of Chop2-GFP-positive cells were normal for at least 3 months, and ChR2-mediated light responses were demonstrated by electrophysiological recordings. CONCLUSIONS: The rAAV2-mediated expression of ChR2 was observed in the inner retinal neurons in the marmoset retina through intravitreal delivery. The marmoset could be a valuable nonhuman primate model for developing ChR2-based gene therapy for treating blinding retinal degenerative diseases.