Some people with FD/MAS may have no symptoms; the bone lesions may be found only because an X-ray was done for some other reason. Others, especially those with more bones involved, may have many symptoms, including pain, enlargement or deformity of the bone, and fractures due to the weakened bone. Symptoms may include bone pain and deformity, a waddling walk, and/or scoliosis (curvature of the spine).
Those who have MAS may have various endocrine problems such as early puberty or over-production of thyroid hormones, growth hormone excess, Cushing’s disease (excess cortisol), and/or low blood phosphate.
The skin may have areas of increased skin pigment, often called café-au-lait macules. The term “café-au-lait,” however, refers to the color of the lesions in light-skinned individuals, which resembles the color of coffee with milk. In dark-skinned individuals, the lesions may be more challenging to see. The pigment distribution pattern is distinctive, often starting or ending abruptly at the midline of the body. The borders tend to be jagged and irregular. The macules are usually present at birth and do not change significantly over a patient’s lifetime.