Which type of tumor is considered a cutaneous T-cell lymphoma?

Mycosis fungoides is classified as a cutaneous T-cell lymphoma due to its origin from mature T-lymphocytes, which are a type of white blood cell involved in the immune response. It typically presents as skin lesions that can vary in appearance, often starting as patches that can progress over time. This malignancy primarily affects the skin and is characterized by a prolonged clinical course.

In contrast, the other options refer to different types of tumors with distinct characteristics and underlying pathophysiology. Paraganglioma arises from the paraganglia and is part of the neuroendocrine tumors, pilomatrixoma is a benign skin tumor originating from hair follicle matrix cells, and squamous cell carcinoma is a type of skin cancer that arises from epithelial cells. None of these tumors are classified as T-cell lymphomas, making mycosis fungoides the correct choice for this question regarding cutaneous T-cell lymphoma.