Differential Diagnosis for Epistaxis and Systemic Symptoms in a 50-year-old Man

Single Most Likely Diagnosis

• Benzene exposure: The patient's history of working in an oil refinery for more than 12 years, coupled with symptoms of easy fatigue, bruising, and weight loss, points towards benzene exposure as the most likely cause. Benzene is a known hematotoxin that can cause bone marrow suppression, leading to anemia, thrombocytopenia, and leukopenia, which can manifest as easy bruising, fatigue, and recurrent epistaxis.

Other Likely Diagnoses

• Carbon monoxide exposure: While carbon monoxide poisoning can cause headache, dizziness, and fatigue, it is less likely to cause the specific combination of epistaxis, bruising, and significant weight loss seen in this patient.
• Lead exposure: Lead poisoning can cause a range of symptoms including fatigue, weight loss, and bruising due to its effects on the hematopoietic system. However, the specific pattern of symptoms and the occupational history make benzene a more likely culprit.

Do Not Miss Diagnoses

• Cyanide exposure: Although less likely given the chronic nature of the symptoms, cyanide poisoning can cause severe systemic effects including cardiovascular and neurological manifestations. It's crucial to consider cyanide exposure, especially in workers in industries that might use or produce cyanide, due to its high toxicity and potential for rapid progression to severe illness or death.
• Mercury exposure: Mercury is a potent neurotoxin, and while it can cause a range of systemic symptoms, the specific pattern of epistaxis, easy bruising, and weight loss is less typical for mercury poisoning. However, given the potential for severe neurological and systemic effects, it should not be overlooked.

Rare Diagnoses

• Other occupational exposures: Depending on the specific processes and chemicals used in the oil refinery, other occupational exposures could potentially explain the patient's symptoms. These might include solvents, heavy metals, or other industrial chemicals, each with its own unique toxicity profile.
• Idiopathic or non-occupational causes: It's also important to consider that the patient's symptoms could be due to non-occupational exposures or idiopathic conditions affecting the bone marrow or coagulation system. However, given the occupational history, these would be less likely explanations.