Entamoeba histolytica is a protozoan parasite that causes intestinal inflammation. A few cases have been misdiagnosed as UC with poor outcomes occurring due to the use of corticosteroids.The most common disease that mimics the symptoms of ulcerative colitis is Crohns disease, as both are inflammatory bowel diseases that can affect the colon with similar symptoms. It is important to differentiate these diseases since their courses and treatments may differ. In some cases, however, it may not be possible to tell the difference, in which case the disease is classified as indeterminate colitis. Crohns disease can be distinguished from ulcerative colitis in several ways. Characteristics that indicate Crohns include evidence of disease around the anus (perianal disease). This includes anal fissures and abscesses as well as fistulas, which are abnormal connections between various bodily structures.Infectious colitis is another condition that may present in similar manner to ulcerative colitis. Endoscopic findings are also oftentimes similar. One can discern whether a patient has infectious colitis by employing tissue cultures and stool studies. Biopsy of the colon is another beneficial test but is more invasive. Other forms of colitis that may present similarly include radiation and diversion colitis. Radiation colitis occurs after irradiation and often affects the rectum or sigmoid colon, similar to ulcerative colitis. Upon histology radiation colitis may indicate eosinophilic infiltrates, abnormal epithelial cells, or fibrosis. Diversion colitis, on the other hand, occurs after portions of bowel loops have been removed. Histology in this condition often shows increased growth of lymphoid tissue.
Sunlight exposure and immunosuppression are risk factors for SCC of the skin, with chronic sun exposure being the strongest environmental risk factor. There is a risk of metastasis starting more than 10 years after diagnosable appearance of squamous cell carcinoma, but the risk is low, though much higher than with basal-cell carcinoma. Squamous cell cancers of the lip and ears have high rates of local recurrence and distant metastasis. In a recent study, it has also been shown that the deletion or severe down-regulation of a gene titled Tpl2 (tumor progression locus 2) may be involved in the progression of normal keratinocytes into becoming squamous cell carcinoma.SCCs represent about 20% of the non-melanoma skin cancers, but 80-90% of those with metastatic potential are located on the head and neck.Tobacco smoking also increases the risk for cutaneous squamous cell carcinoma.The vast majority of SCCs are those of the skin, and are often the result of ultraviolet exposure. SCCs usually occur on portions of the body commonly exposed to the Sun; the face, ears, neck, hands, or arm. The main symptom is a growing bump that may have a rough, scaly surface and flat reddish patches. Unlike basal-cell carcinomas, SCCs carry a higher risk of metastasis, and may spread to the regional lymph nodes,Erythroplasia of Queyrat (SCC in situ of the glans or prepuce in males, M: 733 : 656  or the vulvae in females.) may be induced by human papilloma virus. It is reported to occur in the corneoscleral limbus.