Table 1.
Nonbrain metastatic lesions, structures, and primary sites
| Nonbrain metastatic lesions | Structures | Common primary sites | Don’t-forget primary sites | Comments | |
|---|---|---|---|---|---|
| Frequent | |||||
| Bone Mets | Skull and cervical bone | Breast and lung cancer | Prostate and thyroid cancer | 30% coexist with brain Met | |
| LMC | Meninges, ventricles, and CNs | Breast and lung cancer | Melanoma | > 70% coexist with brain Met | |
| Infrequent | |||||
| Pituitary Mets | Pituitary gland and stalk | Breast and lung cancer | Thyroid cancer | ||
| Pineal gland Mets | Pineal grand | Lung and breast cancers | Melanoma | ||
| Ventricle/choroid plexus Mets | Ventricle/choroid plexus | Lung cancer and RCC | Melanoma and gastrointestinal cancer | RCC Mets cause intratumoral hemorrhage and massive edema | |
| Muscle Mets | HN muscles | Breast and lung cancer | Esophageal cancer | Extraocular muscle is the second most site, next to thigh muscle | |
| Orbital and ocular Mets | Eye and orbit | Breast and lung cancer | Skin cancers | Met can cause retinal detachment | |
| Cutaneous/subcutaneous Mets | Cutaneous/subcutaneous tissue | Lung and breast cancer | HN cancers | One-thirds occur in the HN area | |
| Parotid Mets | Parotid gland | Skin SCC and melanoma | HN cancers and RCC | 90% are from supraclavicular sites | |
| ISCMs | Cervical spinal cord | Lung and breast cancer | Prostate cancer | ISCM is considered, check lung | |
| Direct invasions and PNS | Skull base and HN | HN cancers | Melanoma | PNS: CNs V and VII are common | |
| Double cancers | Nasopharynx and mesopharynx | N/A | N/A | HN cancers and/or lymph node Met should be noted | |
CN cranial nerve, DWI diffusion-weighted images, HN head and neck, ISCM intramedullary spinal cord metastasis, Met metastasis, MRI magnetic resonance imaging, N/A not applicable, PNS perineural spread, RCC renal cell carcinoma, SCC squamous cell carcinoma
Adapted from [9–11, 16, 20, 24, 26–28, 30, 31, 33–36, 39, 41–43, 45–48, 50–56]