The head and neck has the broadest spread of diagnosis codes, probably due to the large number of different sites. The official coding site is here.
Important codes for the head and neck are:
- Most "Cxx.8" codes refer to overlapping malignant lesion within particular site. For instance, A tonsillar lesion that invades the pillars and tonsillar fossa and for which the exact site of origin is indeterminate should be "C09.8 - Overlapping malignant lesion of tonsil"
- Tumours that involve multiple different sites within the pharynx, oral cavity and lip, and for which there is no obvious primary site of origin, should be classified as C14.8 - Overlapping lesion of lip, oral cavity and pharynx
- Note that for the purposes of ICD-10, the nasal cavity, middle ear, sinuses and larynx are coded under 'respiratory organs' (C30-C32).
- I am unsure how to code a lesion that involves the larynx and pharynx for which the primary site can not be determined - perhaps C76.0 (Head and Neck) or C76.8 (Overlapping lesion of ill defined site)
C00 - Lip
The lip includes the vermillion area of the external lip but not the external skin - use C44.3 for that. Lesions localised to the inner or outer aspect of the upper or lower lip should be specified by one of the sub codes. Lesions for which the initial site can not be determined and involve both surfaces of the lip should be coded as C00.8 - overlapping malignant lesion of lip. See below for lesions for which a clear site can not be determined. A difficulty would be a malignancy arising at the vermillion border with the skin - should this be C00.0, C00.8, C44.3, C76.0, or C76.8?