MUC5AC and neoplasm: It is uncommon in the gastrointestinal tract and is classically linked to mucin-rich neoplasia.1 Reports in serrated colorectal lesions are rare; to our knowledge, only 2 cases describe HO within a sessile serrated lesion (SSL), and only one involved the appendiceal orifice.2 Beyond SSLs, HO has been documented across other gastrointestinal neoplasms and settings, which provides context for osseous metaplasia in the colon and appendix.3 We present a recurrent, firm appendiceal-orifice SSL containing HO with a synchronous well-differentiated neuroendocrine tumor (NET).