Follow your doctor's advice and monitor this common affliction. I can barely spell it, let alone find any information in medical books. I've had the condition since 1958, around the same time our water supply had fluoride added to it. Mastocytoma is a benign skin tumor. It is diagnosed by biopsy and blood tests.
Antihistamines relieve symptoms.
Your case is unusual. This condition needs no treatment and is not related to fluoridation of drinking water. The skin lesions may itch, requiring antihistamine creams or pills for relief.