Differential Diagnosis for Skin Lesion

• Single most likely diagnosis
  • Epidermal inclusion cyst: This is the most likely diagnosis given the dermal location, fluid content, and small size of the lesion. Epidermal inclusion cysts are common, benign lesions that can appear as small, protruding bumps on the skin.
• Other Likely diagnoses
  • Sebaceous cyst: Similar to epidermal inclusion cysts, sebaceous cysts are benign lesions that can contain fluid and appear as small bumps on the skin. They are also dermal in nature and can be similar in size to the described lesion.
  • Dermatofibroma: A dermatofibroma is a benign skin lesion that can appear as a small, firm bump. While they are typically solid, some may contain fluid, and their dermal location is consistent with the described lesion.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Metastatic lesion: Although rare, a metastatic lesion from an internal malignancy could present as a small, dermal nodule. It is essential to consider this possibility, especially if the patient has a history of cancer.
  • Merkel cell carcinoma: This is a rare, aggressive skin cancer that can appear as a small, firm nodule. While it is unlikely, it is crucial to rule out this diagnosis due to its potential for rapid growth and metastasis.
• Rare diagnoses
  • Dermoid cyst: A dermoid cyst is a rare, benign lesion that can contain fluid and appear as a small bump on the skin. They are typically congenital and can be dermal in nature.
  • Blue rubber bleb nevus: This is a rare, benign vascular lesion that can appear as a small, blue-purple bump on the skin. While it is unlikely, it could be considered in the differential diagnosis, especially if the lesion has a bluish tint.