Differential Diagnosis for 45 yo Male Patient

The patient presents with bright red blood in the stool and a painful, bleeding nose lesion with a family history of skin cancer. Here's a differential diagnosis organized into categories:

• Single Most Likely Diagnosis
  • Diverticulosis: The patient's complaint of bright red blood in the stool, which started three months ago, is a common presentation of diverticulosis, especially in a 45-year-old male without a family history of colon cancer. The absence of other symptoms like changes in bowel habits or abdominal pain also points towards diverticulosis.
• Other Likely Diagnoses
  • Colon Polyps: Although the patient denies a family history of colon cancer, colon polyps can cause rectal bleeding and are common in this age group.
  • Anal Fissure: The patient's denial of hemorrhoids does not rule out other anorectal conditions like anal fissures, which can cause painful, bright red bleeding.
  • Squamous Cell Carcinoma (SCC) of the nose: Given the patient's family history of skin cancer and the description of the nose lesion (painful, bleeding, with raised borders), SCC is a possible diagnosis, despite the previous benign biopsy.
• Do Not Miss Diagnoses
  • Colorectal Cancer: Although less likely due to the absence of a family history and the patient's age, colorectal cancer must be considered, especially with the symptom of rectal bleeding.
  • Angiodysplasia: This condition can cause recurrent, painless rectal bleeding and is more common in older adults but should not be missed.
  • Basal Cell Carcinoma (BCC) or other skin malignancies of the nose: The previous benign biopsy does not entirely rule out the possibility of a skin malignancy, especially given the family history of skin cancer and the evolving nature of the lesion.
• Rare Diagnoses
  • Blue Rubber Bleb Nevus Syndrome (BRBNS): A rare condition characterized by vascular malformations that can cause gastrointestinal bleeding and skin lesions.
  • Peutz-Jeghers Syndrome: An autosomal dominant disorder characterized by the development of particular types of polyps in the gastrointestinal tract and an increased risk of certain cancers, along with mucocutaneous melanin deposits, which could potentially explain the nose lesion and rectal bleeding if the patient has a previously undiagnosed condition.

Each diagnosis is considered based on the patient's symptoms, family history, and the natural history of the diseases in question. Further diagnostic testing, including colonoscopy for the gastrointestinal symptoms and a repeat biopsy or more detailed examination of the nose lesion, would be necessary to determine the exact cause of the patient's complaints.