Differential Diagnosis for a Large 2.5 Inch Indurated Cyst in the Lateral Arm
- Single Most Likely Diagnosis
- Epidermoid cyst (also known as sebaceous cyst): This is the most likely diagnosis due to the description of the lesion as a large, indurated cyst. Epidermoid cysts are common and can occur anywhere on the body, including the arm. They are usually benign and can become large and firm over time.
- Other Likely Diagnoses
- Lipoma: A lipoma is a benign tumor composed of fat tissue. It can present as a firm, indurated mass and can occur in the arm. However, lipomas are typically softer and more mobile than epidermoid cysts.
- Dermatofibroma: A dermatofibroma is a benign skin growth that can present as a firm, indurated nodule. It is usually smaller than 2.5 inches but can occur in the arm.
- Ganglion cyst: A ganglion cyst is a benign cyst that typically occurs on the wrist or hand but can occur in other areas, including the arm. It is usually smaller and more fluid-filled than an epidermoid cyst.
- Do Not Miss Diagnoses
- Soft tissue sarcoma: Although rare, soft tissue sarcomas can present as a large, firm mass in the arm. It is crucial to consider this diagnosis to ensure timely treatment if it is present.
- Metastatic tumor: In rare cases, a metastatic tumor from another primary cancer can present as a large, indurated mass in the arm. This diagnosis should not be missed, as it requires prompt evaluation and treatment.
- Rare Diagnoses
- Pilar cyst: A pilar cyst is a type of cyst that occurs on the scalp but can rarely occur in other areas, including the arm. It is usually smaller and less firm than an epidermoid cyst.
- Hygroma: A hygroma is a rare, benign cyst that typically occurs in the neck or axilla but can occur in other areas, including the arm. It is usually smaller and more fluid-filled than an epidermoid cyst.
- Neurofibroma: A neurofibroma is a benign tumor of the nerve tissue that can present as a firm, indurated mass in the arm. It is usually smaller and more associated with neurofibromatosis type 1.