Differential Diagnosis for 54-year-old Female with Ruptured Cyst on Left Buttocks
- Single most likely diagnosis:
- Furuncle or Carbuncle: Given the patient's history of morbid obesity and diabetes, which can impair immune function and increase the risk of skin infections, a furuncle (boil) or carbuncle (cluster of boils) is a likely diagnosis. The location at the base of the buttocks' crack, where friction and moisture can contribute to infection, and the description of the cyst as draining and painful, support this diagnosis.
- Other Likely diagnoses:
- Infected Epidermal Inclusion Cyst: The patient's description of a cyst that ruptured could indicate an infected epidermal inclusion cyst, which can become inflamed and painful, especially in areas prone to friction.
- Hidradenitis Suppurativa: Although less common, hidradenitis suppurativa, a chronic skin condition characterized by recurrent, painful abscesses and nodules in apocrine-gland-bearing areas (like the buttocks), could be considered given the location and nature of the patient's symptoms.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Necrotizing Fasciitis: This is a life-threatening infection that requires immediate attention. Although the patient denies fever, chills, or confusion, the presence of a painful, draining lesion, especially in an immunocompromised patient, necessitates consideration of this diagnosis.
- MRSA Infection: Despite the patient's denial of a history of MRSA, the risk factors of diabetes and morbid obesity, along with the nature of the lesion, make it crucial to consider and rule out MRSA infection due to its potential for severe outcomes.
- Rare diagnoses:
- Pilonidal Cyst: Although more common in younger individuals, a pilonidal cyst, which can become infected and present similarly to the patient's symptoms, should be considered, especially given the location at the base of the buttocks.
- Actinomycosis: A rare bacterial infection that can cause abscesses or masses, actinomycosis might present with similar symptoms, especially if the patient has had recent trauma or surgery in the area, though this would be less likely without additional supporting history.