Differential Diagnosis for Large Modular Lesions with Drainage
Single Most Likely Diagnosis
- Chronic Furuncle or Carbuncle: A long-standing, large, modular lesion that is now draining is likely a chronic furuncle or carbuncle, which are infections of the skin and subcutaneous tissue, often caused by Staphylococcus aureus. The chronic nature and drainage suggest a deep-seated infection that has been present for years.
Other Likely Diagnoses
- Cyst or Abscess: A large, modular lesion that has been present for years and is now draining could be a cyst or abscess that has become infected and is draining pus. This could be due to various causes, including bacterial infection or blockage of a gland or duct.
- Hidradenitis Suppurativa: This is a chronic skin condition characterized by recurrent, painful abscesses and nodules, often in areas with apocrine glands, such as the axilla or groin. The lesions can drain and may have been present for years.
- Pilondial Sinus or Cyst: A pilonidal sinus or cyst is a type of skin infection that typically occurs near the tailbone, at the top of the buttocks. It can cause a large, modular lesion that drains and may have been present for years.
Do Not Miss Diagnoses
- Squamous Cell Carcinoma: Although less likely, a large, modular lesion that has been present for years and is now draining could be a sign of squamous cell carcinoma, a type of skin cancer. It is crucial to not miss this diagnosis, as it can be deadly if left untreated.
- Tuberculosis or Atypical Mycobacterial Infection: In rare cases, a chronic, draining lesion could be a sign of tuberculosis or an atypical mycobacterial infection, which can be serious and require specific treatment.
Rare Diagnoses
- Actinomycosis: This is a rare bacterial infection that can cause chronic, draining lesions, often in the face, neck, or chest. It is usually associated with poor dental hygiene, trauma, or immunosuppression.
- Myiasis: In some cases, a large, modular lesion that is draining could be due to myiasis, an infestation of the skin by fly larvae, which can occur in immunocompromised individuals or those with poor hygiene.
- Cutaneous Lymphoma: Although rare, cutaneous lymphoma can present as a large, modular lesion that drains, and it is essential to consider this diagnosis to ensure proper treatment.