Differential Diagnosis for a 59-year-old Male with a Red Papule on Top of Feet
- Single most likely diagnosis:
- Erythema nodosum or superficial thrombophlebitis: These conditions are common causes of red papules on the lower extremities, including the tops of feet, and can be related to various factors such as trauma, infection, or inflammation.
- Other Likely diagnoses:
- Insect bite or sting: This could cause a localized red papule, especially if the patient has been outdoors or exposed to insects.
- Contact dermatitis: Irritation from shoes, socks, or other materials could lead to a red papule on the top of the foot.
- Folliculitis: An infection of the hair follicles could present as a red papule, particularly if the patient has been shaving or has poor foot hygiene.
- Keratosis pilaris: A benign skin condition that can cause small, red bumps on the skin, including the tops of feet.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
- Cellulitis: A bacterial infection of the skin and subcutaneous tissue that can start as a red papule and spread rapidly, potentially leading to serious complications if not treated promptly.
- Erythromelalgia: A disorder that causes burning pain, heat, and redness in the hands and feet, which could be mistaken for a simple red papule but has more severe implications.
- Squamous cell carcinoma or other skin cancers: Although less likely, it's crucial to consider the possibility of skin cancer, especially in older adults or those with a history of sun exposure.
- Rare diagnoses:
- Panniculitis: A group of conditions that involve inflammation of the subcutaneous fat, which could present as a red papule on the top of the foot.
- Erythema multiforme: A skin condition characterized by target-like lesions, which could appear as red papules and is often associated with infections or medications.
- Sweet syndrome (acute febrile neutrophilic dermatosis): A rare condition that can cause red papules or nodules, often accompanied by fever and other systemic symptoms.