Question: Encounter notes indicate that the provider treated a patient with “lumbago NOS.” I’m having trouble locating an ICD-10 code for this condition. Can you help? New Jersey Subscriber Answer: You should report M54.50 (Low back pain, unspecified) for this patient. ICD-10 removed all doubt about this diagnosis code choice when it added new synonyms under M54.50 to include “lumbago NOS.” Star sign: In ICD-10 2022, the synonyms for M54.50 include: *Low back pain *Lumbago NOS The stars beside the synonyms means that the descriptor was revised for 2022 to include these alternate terms.