After an exceptionally rare diagnosis, a lifesaving bone marrow transplant and a near-fatal infection that pushed his body to the brink, Mike Sonnabend is not only alive — he's back to doing what once seemed impossible. 

Mike Sonnabend, a husband and father to three sons, enjoys being active — not just physically but also in the Rochester, Minnesota, community. The special education teacher and head coach of cross-country and track was preparing for an adventurous Scouting trip to the Florida Keys with his oldest son, Sam, and needed to complete a physical as part of the trip requirements.  

During the exam, his Mayo Clinic family medicine physician, Dr. Lori Bates, noticed that his spleen felt enlarged. Mike didn't think anything of it — he was feeling fine and had no symptoms. But after undergoing several tests and a bone marrow biopsy before leaving for his trip, he had a feeling he would come back to bad news.  

He was right. On July 3, 2014, Mike was diagnosed with a serious and complex disease consisting of leukemia — a cancer of the body's blood-forming tissues, including the bone marrow and the lymphatic system — and a bone marrow failure disorder, where blood cells don't develop normally. It's an incredibly rare condition — with very few cases worldwide — and is incurable with standard treatments.  

Mike's hematologist, Dr. Mrinal Patnaik, explained that a bone marrow transplant, a procedure that infuses healthy blood-forming stem cells into the body to replace bone marrow that's not producing enough healthy blood cells, would be the most effective treatment.  

"I knew that I couldn't fight this on my own. My Mayo Clinic care team is the experts, so I let them take care of the fighting, and I focused on what I could control — my family, my mindset and my recovery." 

As news of Mike's diagnosis spread, his family, friends, colleagues and community members quickly rallied around him and offered support.  

A rare diagnosis becomes even more complex 

Mike was referred to Dr. Mithun Shah, a Mayo Clinic transplant hematologist to ensure he was physically prepared for the transplant.  

All was going well with Mike's pretransplant testing until a pulmonary function test showed his lung function was much lower than expected. Because bone marrow transplants involve extensive treatments with a long, complex recovery, unexplained lung issues could make the procedure too dangerous. 

"We have a rare disease, and now there is a unique lung presentation. Our culture of collaboration at Mayo Clinic is where we shine. I picked up the phone and called my colleagues in hematology, pulmonology, pathology and other specialties — and we worked together, in real time, to assess risks and adapt Mike's treatment plans," says Dr. Shah.  

Dr. Shah referred Mike to Dr. Vivek Iyer, a Mayo Clinic pulmonologist, to help diagnose and treat the lung problem.  

"Transplant patients often have complex medical issues affecting multiple organ systems, so different specialties often need to collaborate expeditiously to solve critical issues that could delay or even prevent a successful transplantation," says Dr. Iyer.  

A lung biopsy confirmed that Mike had eosinophilic pneumonia, a rare and serious inflammatory lung condition. When steroids failed to resolve it, Dr. Iyer prescribed a monoclonal antibody-based therapy typically used for severe asthma that stabilized his lungs and kept his transplant on track — until another barrier emerged: Mike's enlarged spleen began draining his energy and appetite. In December 2019, doctors removed the massive organ, allowing his care team to move forward with his carefully planned transplant approach that would treat his leukemia while protecting his lungs.  

It worked. Mike had a successful transplant in 2020.  

Driven by a mindset focused on progress, Mike was back to coaching, teaching and running within a time frame that was "absolutely incredible," according to Dr. Shah.  

"My approach was to take the next step, trust the process and keep moving forward," says Mike.  

That same resilience would become even more evident five years later, when his journey took another dramatic turn.  

From stability to a sudden, life-threatening turn 

It was April 14, 2025. Around mid-morning, Mike began to feel fatigued, feverish and disoriented. He left work early and went to lie down, setting an alarm so he could make it to track practice that afternoon.  

But Mike wasn't well enough to make it to practice. Sam, who coaches with his dad, remembers having a sinking feeling, especially because he hadn't heard from him.  

"My dad would never not show up without letting me or the other coaches know, let alone even miss a day," says Sam.  

Sam went home after practice to check on his dad. Mike had slept through his alarm, had a high fever and was disoriented. Sam and his mom took him to Mayo Clinic's Emergency Department.  

"I don’t remember much," says Mike. "I remember going to the emergency room, and then it went black." 

Doctors soon determined he was battling bacterial meningitis, an infection that triggered overwhelming sepsis. For transplant patients like Mike, whose immune systems are compromised and who no longer have a spleen, even common bacteria can become life-threatening. 

Within hours, multiple organs began failing. His kidneys shut down, his blood pressure crashed and his body's clotting system began breaking down. He was transferred to the intensive care unit (ICU), where his condition became so dire that his family was called in to prepare for the worst. 

Mike's care again became a full-scale, multidisciplinary effort. Specialists across Mayo Clinic mobilized simultaneously — including experts in critical care, infectious diseases, nephrology, transplant medicine, vascular medicine, rehabilitation and more, meeting in real time to exchange ideas and make quick decisions together. 

"Mayo Clinic’s team-based approach is critical in situations like this. We needed everyone's expertise to give Mike the best chance of survival," says Dr. Shah.  

For Mike and his family, that collaboration was visible every day. 

"There was so much brainpower in that room, you could almost feel it," Mike says. "You could see the wheels turning. Everybody was trying to think of every possible thing to save me." 

Sam, who had since become a nurse after being inspired by his father's earlier cancer journey, helped guide the family through the most difficult moments.  

"Mayo Clinic did a great job of individualizing our care and really being there for us as a family," says Sam. "They gave us all the time we needed to ask questions — I felt like there wasn't a time clock on any of our interactions." 

Mike's journey was precarious, and at several points, his survival remained uncertain. But through relentless determination — and the coordinated expertise of dozens of Mayo Clinic specialists — Mike made another extraordinary recovery.  

Survival fueled by resilience and expertise 

"That was one of the toughest cases of my life," says Dr. Shah of Mike's most recent hospitalization. "Him pulling through and walking out of the ICU was one of my most satisfying moments." 

One year later, Mike feels good. He has his strength back, is exercising and is almost back to 100%.  

"I shouldn’t be here. I threw so many rare situations at my care team, and each time, they saved my life," says Mike. "There's no way you can get expertise like this anywhere else. It's incredible." 

Sam is grateful for the time he spent with his dad throughout his healthcare journey. 

"My dad is resilient, strong and the bravest person I know," says Sam. "I could tell he was scared, but he would always say, 'I have to keep going. I have to keep listening to the doctors. I have to keep taking my medicine, and eventually I am going to get out of it.' And despite all the odds, he did it."  That mindset — paired with his multidisciplinary care team working together — helped transform what could have been an ending into an extraordinary comeback.

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