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).
Many white lesions involving the oral mucosa are benign and do not require treatment. These include congenital or developmental conditions such as white sponge nevus, keratosis follicularis, hereditary benign intraepithelial dyskeratosis, pachyonychia congenita, and Fordyce granules.he lesions of reticular OLP are typically painless and occur most frequently on the buccal mucosa, gingiva, and tongue. When OLP involves mucosal erythema along with the whitened lesions (termed erosive lichen planus), the condition can be painful. OLP is a chronic disease without a known cure.