Differential Diagnosis for a 44-year-old with a Lump under the Buttock
- Single most likely diagnosis:
- Furuncle or Carbuncle: Given the patient's history of getting boils that pop and drain, and the current presentation of a lump with mild redness and induration, a furuncle (boil) or carbuncle (a group of boils) is the most likely diagnosis. The fact that this one did not drain with attempted lancing or popping suggests it might be a deeper or more complex infection.
- Other Likely diagnoses:
- Abscess: An abscess is a collection of pus that has built up within the tissue of the body. The patient's attempt to lance the lump and the lack of drainage could indicate a deeper abscess that hasn't come to a head yet.
- Cyst: A cyst, such as a pilonidal cyst, could present similarly, especially if it becomes infected. The location under the buttock is common for pilonidal cysts.
- Folliculitis: An inflammation of the follicles, which could be a precursor to a furuncle or could present with similar symptoms if severe.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Necrotizing Fasciitis: Although rare, this is a life-threatening condition that requires immediate attention. The presence of severe pain out of proportion to the appearance, rapid progression, and signs of systemic infection (fever, tachycardia) would raise suspicion.
- Cellulitis with deeper infection: While cellulitis itself is not immediately life-threatening, if it progresses to involve deeper tissues or spreads, it can become serious. Signs of systemic infection or rapid spread would necessitate urgent evaluation.
- Rare diagnoses:
- Hidradenitis Suppurativa: A chronic skin condition that can cause painful, inflamed bumps in the skin, often in areas where skin rubs together. It could be considered if the patient has a history of similar lesions in other areas.
- Lipoma or other benign tumors: Although less likely given the history of boils and the current symptoms, a lipoma or other benign tumor could present as a lump under the buttock. However, these are typically not painful or inflamed.
- Squamous Cell Carcinoma or other skin cancers: Very rare but could present as a non-healing lump or sore. Given the patient's attempt to lance and the lack of drainage, along with the induration, it's less likely but should be considered if the lesion does not resolve with treatment.