Could MS be misdiagnosed and called SCLC? - 1270088

After my father, age 75, was admitted into his local hospital he received a diagnosis of a delerium caused by vascular dementia. (There had been limited evidence of dementia symptoms prior to this). He was in the hospital for about 2 weeks and released. A week later he was taken to a larger hospital. He had bp extremes, confusion, and seizures. As they were trying to diagnose the reason for the seizures, they found a spot on his lung. A lung specialist did a brachioscopy. The oncologist's assistant met with us the next day and said he had limited SCLC (lower right lobe and lymph nodes) and the 8 biopsies done had confirmed it. The odd part was when she asked me how long my dad had MS as he had MS markers in his brain. I said he didn't to my knowledge. His sister has had it for many years though.

My dad denied treatment and we were sent home with hospice. The doctors said it was likely for him to live 4-6 months- although it was just an estimate. It has been 4 months since his original diagnosis and my father has had few symptoms. Symptoms he has experienced include fatigue, worsening vision, and coughing up spots of blood in his spit. I've read that symptoms of SCLC aren't apparent until the cancer is in the extensive stage. Because he denied treatment, he would have to pay for a 2nd opinion. My sister and I are his caregivers and have adapted our work schedule to care for him. We are trying to determine what needs to happen in the future for him and us.

My questions are, Could SCLC be misdiagnosed? How could we tell the difference between MS and SCLC?

Thank you.