• Rashes are broadly classified as: Centrally distributed maculopapular; peripheral; confluent desquamative erythematous; vesiculobullous; urticarial; purpuric.• Centrally distributed maculopapular rashes are usually due to virus infection or drug-related eruptions.• Rubella/German measles: Fever - not high-grade; rash scattered; fever disappears when rash appears; occipital, epitrochlear lymph nodes appear; no significant coryza; short duration and relatively benign disease.• Roseola infantum (HSV 6): Rash appears on 4th/5th day; fever appears by crisis or subsides by lysis; caused by HSV 6; called as sixth disease; may cause febrile seizures, encephalitis, aseptic meningitis.• Erythema infectiosum (fifth disease): Fever for 3-5 days and rash on face.• Differential diagnoses: V (vascular) - Infarcts, cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), arteriovenous malformation (AVM); I (infectious) - Lyme, syphilis, HIV, HTLV, TB, herpes, mycoplasma, Whipple disease, fungal infections, neurocysticercosis; T (traumatic) - Spondylotic myelopathy; A (autoimmune) - Neuromyelitis optica (NMO), acute disseminated encephalomyelitis (ADEM), vasculitis, Behcets syndrome, sarcoidosis, lupus, scleroderma, celiac disease; M (metabolic/toxic) - Central pontine myelinolysis, B12 deficiency, B6 deficiency, radiation, hypoxia, TNF- blockers; I (idiopathic/genetic) - Friedreich ataxia, Susac syndrome, migraine; N (neoplastic) - Lymphoma, glioma, paraneoplastic encephalomyelitis; S (psychiatric).