Differential Diagnosis for a 55-year-old Male with a Skin Lesion on the Left Neck
Single Most Likely Diagnosis
- Infected skin tag or sebaceous cyst: The description of a skin tag that became infected, filled with pus, and then drained, followed by the formation of a black mass, is consistent with an infected skin tag or sebaceous cyst that has undergone necrosis.
Other Likely Diagnoses
- Furuncle or carbuncle: These are infections of the hair follicle and surrounding tissue, which can present with pus, drainage, and necrotic tissue, similar to the patient's symptoms.
- Abscess: A collection of pus that has built up within the tissue, which can occur on the neck and present with similar symptoms.
- Infected epidermoid cyst: Similar to a sebaceous cyst, an epidermoid cyst can become infected, leading to pus, drainage, and potentially necrotic tissue.
Do Not Miss Diagnoses
- Necrotizing fasciitis: Although less likely, this is a life-threatening condition that requires immediate attention. It is characterized by necrosis of the fascia and surrounding tissue, which can present with similar symptoms, including a black eschar.
- Malignancy (e.g., basal cell carcinoma, squamous cell carcinoma): Although rare, certain types of skin cancer can present with ulceration, drainage, and necrotic tissue, making it essential to consider and rule out these conditions.
Rare Diagnoses
- Pyoderma gangrenosum: A rare skin condition characterized by ulceration and necrotic tissue, which can present with a similar appearance to the patient's symptoms.
- Mycobacterial infection (e.g., Mycobacterium tuberculosis): Certain mycobacterial infections can cause skin lesions with necrotic tissue and drainage, although this would be a rare cause of the patient's symptoms.