A pigmented intradermal nevus can be dark, but it is a smooth, raised papule, not a dilated follicular opening with a keratin plug like an open comedo.
A pigmented BCC may have dark spots, but it is a malignant tumor with other features like a pearly border, not a simple blocked pore.
A small, dark SK can look like a large blackhead, but it has a waxy, "stuck-on" quality and is a surface growth, not a follicular plug.
