Lung Cancer ICD-10-CM codes

Category C34 is organized by anatomic location: C34.0- main bronchus, C34.1- upper lobe, C34.2 middle lobe (right lung only, so no laterality character), C34.3- lower lobe, C34.8- overlapping sites, and C34.9- unspecified part. The fifth character reports laterality: 0 unspecified, 1 right, 2 left. C34.90 is unspecified part of unspecified lung and should only be used when neither lobe nor side is documented; imaging and pathology reports usually specify both, so C34.11 or C34.31 (right upper or lower lobe) and C34.12 or C34.32 (left) are the codes to look for.

Histology (small cell, non-small cell, adenocarcinoma, squamous cell) does not change the C34 code. Carcinoid tumors of the lung are the exception and go to C7A.090. Secondary (metastatic) tumors in the lung from another primary are C78.0-, not C34. When lung cancer spreads within the chest, add C77.1 for intrathoracic lymph node involvement, C78.2 for pleural metastasis, or C79.31 for brain metastasis.

Sequence the malignancy first when the encounter is for evaluation or treatment of the cancer itself; sequence Z51.11 (chemotherapy) or Z51.12 (immunotherapy) first when the admission is solely for that therapy. Malignant pleural effusion is J91.0 with the lung cancer coded first.

Tobacco status affects both quality reporting and risk adjustment: add F17.210 for current cigarette dependence, Z87.891 for personal history of nicotine dependence, or Z77.22 for secondhand smoke exposure. Z85.118 (personal history of other malignant neoplasm of bronchus and lung) is used only after treatment is complete and there is no evidence of disease.