Lambert-Eaton syndrome, unspecified

This code represents Lambert-Eaton Myasthenic Syndrome (LEMS), an autoimmune disorder affecting the neuromuscular junction. It is characterized by muscle weakness, particularly in the proximal limbs, often associated with small cell lung cancer (SCLC) or other autoimmune conditions.

Assign this code when the medical record documents a diagnosis of Lambert-Eaton syndrome without further specification of its underlying cause or associated conditions. This is appropriate when the provider has not yet determined if it's paraneoplastic, autoimmune, or drug-induced.

• Do not use this code if the underlying cause of LEMS (e.g., small cell carcinoma) is known and documented; instead, code the specific type.
• Consider sequencing this code after the malignancy code if LEMS is paraneoplastic and the malignancy is the primary reason for the encounter.
• Review documentation carefully for any mention of associated conditions or specific types of LEMS to ensure the most precise code is selected.