Coal forms from the accumulation of plant debris, usually in a swamp environment. When plant debris dies and falls into the swamp the standing water of the swamp protects it from decay. Swamp waters are usually deficient in oxygen, which would react with the plant debris and cause it to decay.
Porokeratosis is generally considered to be a benign condition though malignant transformation has been seen in all but the punctate variety, necessitating regular followup of patients with porokeratosis (Maubec et al., 2005; Sasson & Krain, 1996).
Telangiectasia macularis eruptiva perstans Nathalie Q Nguyen MD Dermatology Online Journal 10 (3): 1 From the Ronald O. Perelman Department of Dermatology, New York University Abstract. A 45-year-old man presented with lesions clinically and histologically consistent with telangiectasis macularis eruptiva perstans (TMEP). TMEP is a rare form of mastocytosis, which is localized to the skin, although systemic involvement has been reported.