MUC5AC and metastatic neoplasm: Histologically, the seromucinous glands seen in CSSLs usually do not invoke diagnostic consideration of metastatic tumor, since they are cytologically bland, show perfect preservation of acinar pattern, lack mitotic activity, and are histologically analogous to incidental Erdheim rests – except for the fact that they are several-fold larger and symptom-generating along with the mucin they produce.