ICD-10 also establishes new myositis code. If your family physician diagnoses a patient with fibromyalgia, your only code choice under ICD-9-CM is 729.1 (Myalgia and myositis, unspecified). In October 2013 when ICD-10 goes into effect, three specific codes will replace this unspecified one: These conditions are characterized by muscle or musculoskeletal pain and soft tissue or muscle tenderness. Fibromyalgia patients also experience stiffness, general fatigue, and sleep disturbances. Symptoms of varying intensities increase and decrease over time. ICD-10 change: