Clinical diagnosis
Case 112
【Progress】Colonoscope revealed stenosis from anus to rectum (Rb) and rectal-anal fistula with hard induration. Biopsy of the induration revealed adenocarcinoma. The tumor got growing invasively from anal fistula to prostate gland along with right rectal wall with swollen inguinal lymphnodes. It indicated multidisciplinary treatment such as radiotherapy, chemotherapy and surgical resection. Then, he was introduced to university hospital.
【Discussion】
As anal disorders, external and internal hemorrhoids, anal fissure, anal abscess & fistula and anal cancer are listed. External hemorrhoids situate below the dental line and internal hemorrhoids situate above the dental line. Internal hemorrhoids come from superior hemorrhoids plexus and have visceral innervation, indicating being painless, while external hemorrhoids come from inferior hemorrhoids plexus and have somatic innervation, indicating being painful. Thrombosed or enlarged external hemorrhoids often present as pain. The pathogenesis of hemorrhoids is not fully clarified but related to intraabdominal pressure such as straining, constipation, pregnancy and long-sitting position especially squat position (1).
Anal fissure is a linear tear or ulcer in the anal mucosa distal to the dental line. The etiology of anal fissure is also not clarified. However, it is thought that the initial hurt is trauma from hard stool, inducing painful bowel evacuation. The posterior wall of anus is susceptible to be injured (1, 2). The blood flow of posterior anal part is reported to be lower than other quadrant parts, being the most poorly perfused (1, 2). Further, in patients with anal fissure, hypertrophy of internal sphincter muscle is significantly observed, inferring to elevate intraluminal pressure and reduce blood flow (2). However, posterior anal part might be susceptible to hurt simply because it exists between hard stool and the presence of sacrum, while anterior and bilateral anal parts are surrounded by the soft tissue that hard stool hardly hurts.
Anal abscess and anal fistula is a serial happening. At first, anal abscess arises from a tiny anal gland which is infected and enlarged with pus under the anal skin. Mostly, anal abscess is located near the anal opening. Then, anal abscess drained spontaneously to the skin, making a narrow passageway, like a small tunnel between anal canal and skin surface which is called anal fistula. It sometimes discharges pus or bloody fluid. The conversion of abscess to fistula occurs in approximately 40% to 50% of cases (3, 4).
Our case had not external hemorrhoids, internal hemorrhoids and anal fissure but anal fistula for 15 years without radical treatment. Enhanced CT using contrast medium showed neoplasm invasively proliferated from beneath the anal skin to near the prostate gland along with the right rectal wall via the anal fistula. Histological examination of biopsy revealed adenocarcinoma. Because of the possible invasion to prostate gland and inguinal lymphnodes metastasis, multidisciplinary treatment is required. He was forty six year-old, relatively young for getting malignant tumor. Neglecting the treatment for anal fistula beckoned the invasive cancer in our case. We hope that our case becomes warning for patients with remaining anal fistula.
【Summary】
We present a forty six year-old male suffering from bloody feces and constipation. He had rectum-anal fistula without treatment for 15 years. Enhanced CT using contrast medium showed neoplasm invasively proliferating from beneath the anal skin to near the prostate gland along with the right rectal wall via the anal fistula. Histologic examination of biopsy revealed adenocarcinoma. Multidisciplinary treatment was required to treat this advanced cancer. He was relatively young for getting advanced cancer. Our case may become warning that people with remaining anal fistula must get the radical treatment as early as possible. We should keep in mind that anal abscess which originates from tiny anal gland arise near the anal opening, drained spontaneously to the skin, making anal fistula. Anal fissure occurs often at the posterior wall of the anus because the posterior wall exists between hard stool and the presence of sacrum. External and internal hemorrhoids are sequestrated by the dental line, and external hemorrhoids have somatic innervation, indicating painful, while internal hemorrhoids have visceral innervation, indicating painless.
【References】
1.Foxx-Orenstein, AE, et al. Common Anorectal Disorders. Gastroenterol Hepatol (N Y). 2014 May; 10(5): 294–301. PMCID: PMC4076876
2.Ram E, et al. Internal Anal Sphincter Function Following Lateral Internal Sphincterotomy for Anal Fissure: A Long-term Manometric Study. Ann Surg. 2005 Aug; 242(2): 208–211. doi: 10.1097/01.sla.0000171036.39886.fa PMCID: PMC1357726 PMID: 16041211
3.Abcarian H. Anorectal infection: abscess-fistula. Clin Colon Rectal Surg. 2011;24(1):14–21. [PMC free article] [PubMed]
4.Sainio P. Fistula-in-ano in a defined population. Incidence and epidemiological aspects. Ann Chir Gynaecol. 1984;73(4):219–224.
2018.7.11