Differential Diagnosis for Round and Raised Lesion on Back of Neck

Single Most Likely Diagnosis

• Seborrheic Keratosis: A common, benign skin growth that can appear as a round, raised lesion, often with a scabby or crusty surface initially. The location on the back of the neck and the description fit well with this diagnosis.

Other Likely Diagnoses

• Basal Cell Carcinoma: A type of skin cancer that can present as a round, raised lesion. Although less common than seborrheic keratosis, its potential for malignancy makes it a consideration, especially if the lesion has been changing or has an unusual appearance.
• Squamous Cell Carcinoma: Another form of skin cancer that can appear as a raised, scabby lesion. It's less common than basal cell carcinoma but more aggressive.
• Keratoacanthoma: A low-grade, or sometimes considered benign, tumor that can mimic squamous cell carcinoma. It often appears as a round, raised lesion with a central crater.
• Dermatofibroma: A benign skin growth that can appear as a round, raised lesion, often resulting from minor injury, which could initially appear scabby.

Do Not Miss Diagnoses

• Malignant Melanoma: Although less likely given the description, melanoma is a deadly skin cancer that can present in various forms, including as a new, changing, or unusual mole. The "ABCD" rule (Asymmetry, Border, Color, Diameter) is used to evaluate suspicious lesions.
• Metastatic Skin Lesion: In rare cases, a skin lesion could be a metastasis from an internal cancer. This would be extremely unusual for a first presentation but should be considered in patients with a known history of cancer.

Rare Diagnoses

• Cylindroma: A rare, benign skin tumor that can appear as a round, raised lesion. It's often associated with multiple lesions and can be part of a genetic syndrome.
• Trichoepithelioma: A rare, benign skin tumor originating from hair follicles, which can present as a round, raised lesion.
• Pilomatrixoma: A rare, benign skin tumor that originates from the hair follicle matrix and can appear as a firm, raised lesion, sometimes with a bluish tint.

Each of these diagnoses has a different level of urgency and implications for treatment, ranging from benign lesions that may not require treatment to potentially deadly cancers that demand immediate attention. A thorough examination, possibly including a biopsy, is necessary to determine the exact nature of the lesion.