**Core Concept**
Cock's peculiar tumour is a rare, benign skin lesion characterized by a firm, painless nodule, typically found on the skin of the hands or feet. It is a type of cutaneous squamous cell carcinoma in situ, also known as Bowen's disease, but with distinct histopathological features.

**Why the Correct Answer is Right**
The tumour is named after the British dermatologist Arthur Cecil Porritt, who described it in 1906. It is believed to be a variant of Bowen's disease, with the presence of dysplastic keratinocytes and a characteristic 'warty' histological appearance. The exact pathogenesis of Cock's peculiar tumour is unclear, but it is thought to result from prolonged exposure to ultraviolet radiation.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because Cock's peculiar tumour is not a type of basal cell carcinoma. Although both conditions are benign skin lesions, they have distinct histopathological features and clinical presentations.
* **Option B:** This option is incorrect because Cock's peculiar tumour is not a type of dermatofibroma. Dermatofibromas are benign skin lesions that typically present as small, firm nodules, but they have a different histological appearance and clinical behavior compared to Cock's peculiar tumour.
* **Option C:** This option is incorrect because Cock's peculiar tumour is not a type of melanoma. Although melanomas are also skin cancers, they have distinct clinical and histopathological features that differentiate them from Cock's peculiar tumour.

**Clinical Pearl / High-Yield Fact**
Cock's peculiar tumour is a rare but distinctive skin lesion that should be considered in the differential diagnosis of firm, painless nodules on the hands or feet. It is essential to perform a thorough histopathological examination to confirm the diagnosis and rule out more aggressive skin cancers.

**Correct Answer: C. A type of cutaneous squamous cell carcinoma in situ.**