Squamous cell carcinoma of rectum presenting in a man: a case report

Background Primary squamous cell carcinomas of the colorectum are very uncommon. Until now, to the best of our knowledge, only 114 cases of squamous cell carcinoma in the colorectum exist in the reported literature. Here we report a case of squamous cell carcinoma of the rectum in the ethnic Kashmiri population in northern India. Case Presentation The case of a 60-year-old male patient (Asian) with a pure squamous cell carcinoma of the rectum is presented here. The patient underwent a curative surgery with concomitant chemotherapy. Two years after the initial curative resection of the tumor he is still alive. Conclusion The prognosis for squamous cell carcinoma of the colorectum is worse than for that of adenocarcinoma, because of the delayed diagnosis. The etiopathogenicity of squamous cell carcinoma of the colorectum is discussed. Surgical resection of the lesion seems to be the treatment of choice. Chemotherapy also helps in improvement of the prognosis.


Introduction
The occurrence of squamous cell carcinomas (SCC) in the colorectum is a rare entity representing a small fraction of colorectal malignancies, since more than 90% of colorectal diseases are adenocarcinoid tumors [1]. Very little information is available in the literature about the etiology, prognosis and optimal treatment of this malignancy [2]. Here in this study, we describe a patient with SCC of the rectum who underwent a lower anterior resection (LAR) for the possible treatment of the malignancy.

Case presentation
A 60-year-old male patient from an urban area of Kashmir (Asian) visited the Department of General Medicine of our institute with the chief complaints of severe lower-abdominal pain for the past eight months. The patient also complained of severe constipation, nausea, vomiting, anorexia, loss of appetite, abdominal cramps, incontinence of faeces and weight loss during the past four months. He experienced profuse bleeding from the rectum for the last month. Initial interviews with the patient revealed that the he was a heavy smoker and frequent user of noon-chai (Salt tea), meat and pickles. On examination the patient was found to be anemic. Digital rectal examination revealed an ulcero-infiltrative lesion with restricted mobility about 4 cm from the anal verge on the left lateral wall. A colonoscopy confirmed the rectal examination and biopsies taken at the time of the colonoscopy revealed squamous cell carcinoma (SCC) of basal cell type in the first histopathological examination. The report was re-confirmed by a second independent pathologist. A Contrast-Enhanced Computed Tomography (CECT) of the chest, abdomen and pelvis was also done but no lesions were found in any other site than the rectum. The lesion was without any fat stranding or lymphadenopathy. Furthermore, following the provisional diagnosis, the patient was referred to the Department of General Surgery for radical treatment, where he underwent LAR of the rectum using the standard technique of mesorectal excision ( Figure 1). The continuity of the gut was restored by a circular stapler for low colorectal anastomosis with formation of a colonic pouch. The colonic pouch takes over the function of rectal reservoir which is lost after excision of the middle and lower rectum. Microscopic examination of the resected lesion demonstrated a 2.5 cm × 3 cm SCC tumor of the rectum infiltrating the serosa. The margins of the excised tissue were found to be free of the tumor. However, four regional lymph nodes were also infiltrated by the metastatic SCC cells. The liver and the rest of the organs were free of any metastasis. The slides were reviewed by a third histopathologist who reported the lesion as poorly differentiated squamous cell carcinoma. The stage of the tumor was found to be T 3 N 2 M o . The post-operative period was uneventful. Post-operatively the patient received four cycles of chemotherapy with cisplastin and 5-fluorouracil for five days. The patient is on two years of follow-up and has not shown any evidence of recurrenceas of the present time.

Discussion
Colorectal cancer (CRC) is the third most common cause of cancer-related death in the world [3]. Almost 90% of CRC are adenocarcinomas, while the remaining 10% are made up of carcinomas, sarcomas and lymphoid tumors [1]. The occurrence of SCC in the gastrointestinal tract (GIT) is a rare phenomenon, and its occurrence in the colorectum is extremely unusual [4]. The incidence of SCC of the colorectum has been reported to be almost 0.1 to 0.25 per 1000 CRC [4,5]. A look into the research work and the reported cases of SCC dates back to 1907, when Herxheimer reported adenosquamous carcinoma of the cecum but it was in 1919 when the first case of pure SCC of the colon was reported by Schmidtmann [6] in a 65-year-old man [7]. It was not until 1933 that the first case involving the rectum was subsequently described by Raiford [8]. In India, Bhat et al. [9] reported the first case of pure SCC of the colon in 1993 in a 55-year-old female from the southern part of the country. Until now almost 120 cases of SCC have been reported from all over the world (See Table 1). Surprisingly, a study from Russia reported 107 cases of SCC from a single center alone [10] but there has been no such reports of high incidence of SCC in the colorectum from any other part of the world.
Before the diagnosis of primary SCC of colorectum is made, certain criteria must be fulfilled as given by Williams et al. in 1979 [11]. This criteria includes: (A) absence of evidence of squamous cell carcinoma of any other part of the body, ruling out any chance of possible metastasis from any organ to the colorectal site; (B) exclusion of any proximal extension of anal squamous cell carcinoma; (C) absence of fistulous tract lined by squamous cells; and (D) confirmation of SCC by histological analysis [1,4,12]. All of these criteria were fulfilled by our case.
A look at the available literature reveals that squamous cell carcinoma of the colorectum affects individuals with a mean age of 55 to 60 years Women are more frequently predisposed to SCC than men, around 66% of cases occurred in women and 34% in men. Furthermore, SCC occurs in concomitance with an advanced tumor stage (Duke's C) [4,13]. Since SCC of the rectum is a rare tumor, epidemiological data constituting patient demographics, risk factors and natural history are lacking in the literature. The clinical characteristics of the patients with SCC of the colorectum are similar to those with adenocarcinoma: rectal bleeding, abdominal pain, change in bowel habits and weight loss [4]. Because of the rare nature of this malignancy the prognosis for patients is difficult to establish, Comer et al. suggested a poorer prognosis for patients with colorectal SCC than adenocarcinoma [1,4,14].
Almost four different pathophysiological theories regarding the origin of squamous cell carcinoma of the colorectum have been proposed in the literature so far. These can be summarized as: (A) Proliferation of uncommitted basal cells into squamous cells which undergo malignant transformation following mucosal injury [15]; (B) Ability of pluripotent stem cells to undergo spontaneous squamous differentiation [16]; (C) Squamous metaplasia of glandular epithelium resulting from chronic inflammation or irritation, secondary to inflammatory bowel disease [17], infection [18] or radiation [19]; (D) Origin from embryonal nests of ectodermal cells; and (E) Arousal of carcinomas from preexisting adenomas or adenocarcinomas [7,20].

Conclusion
In conclusion, advanced colorectal SCC has a poor prognosis. Since colorectal SCC is a very rare disease, treatment selection is difficult. However, surgical resection and adjuvant chemotherapy [21] is a better approach to the treatment of colorectal SCC.

Consent
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available with   the corresponding author of this manuscript and is accessible for review by the Editor-in-Chief of this journal