initial assessment, 1439 management, 1439 Mannitol, 657 , 1388 Maple syrup urine disease, 333 Marcus Gunn pupil, 187 , 190 Marfanoid body habitus, 522 Marfan syndrome, 325 , 330 , 362 , 369 Marijuana and synthetic cannabinoids, 337 ataxia from, 108 , 108 t Marijuana smoking, 1073 –1074 Marine invertebrates coelenterata phylum (cnidaria), 706 –707 anthozoa, 707 hydrozoa, 707 scyphozoa, 707 echinodermata phylum, 707 –708 Marine vertebrates, 708 –709 catfish, 709 scorpaenidae, 708 –709 sharks, 708 stingrays, 708 Masks, 49 –50 Masses in aerodigestive tract, 909 Mass lesions, 482 Mastalgia, 114 Mastitis, 110 , 111 t, 112 –113 Mastocytomas, 465 Mastocytosis, 445 –446 , 446 f Mastoiditis, 157 McCune–Albright syndrome, 466 MDMA (Ecstasy), 1074 –1075 Mean corpuscular volume (MCV), 419 , 423 , 423 t Measles, 643 , 847 Measles (rubeola), 313 Measles encephalitis, 891 Measles virus, 475 Meatal stenosis, 1335