A 67-year-old man with returning melanoma (a kind of skin cancer) was found to have systemic mastocytosis (SM) after genetic testing on his tumor showed unusual results, according to a recent case report published in the journal Virchows Archiv.
The patient had melanoma removed from his back sixteen years earlier, but later developed fluid around his lung. Tests showed the melanoma had spread. Doctors ran special genetic tests on the cancer to help decide treatment. These tests showed the expected melanoma mutation, but also showed other gene changes that are usually seen in blood disorders. Because of this, doctors decided to check his bone marrow (the part of the body that makes blood cells) more closely.
The bone marrow test showed two problems. First, there were too many mast cells, a type of immune cell that can build up in people with SM. Second, the bone marrow was not making healthy blood cells, which is a sign of myelodysplastic syndrome (a type of cancer).
Blood tests also showed high levels of the protein tryptase in the blood, which is another sign of SM.
Together, all the test results suggested that the patient had SM along with myelodysplastic syndrome at the same time.
“This diagnosis fits within the overall category of SM with an associated myeloid neoplasm,” the study’s authors said.
Read more about SM testing and diagnosis
In this case, the mast cells also did not have the common mutation that doctors usually see in SM (KIT D816V), which made the diagnosis harder.
Doctors said this case is important because the hidden blood disease was only discovered after genetic testing on the skin cancer. It shows that unusual genetic results should be checked carefully, since they may point to another serious condition that needs treatment.
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