Blastic Plasmacytoid Dendritic Cell Neoplasia
Blastic plasmacytoid dendritic cell neoplasm is a rare and aggressive blood cancer that often appears first as skin lesions, affecting fewer than 1,000 people each year in the United States, with new treatments now offering hope for patients with this challenging disease.
Table of contents
- What Is Blastic Plasmacytoid Dendritic Cell Neoplasm?
- Who Gets This Disease?
- How the Disease Shows Itself
- How Doctors Identify the Disease
- Treatment Approaches
- What to Expect
What Is Blastic Plasmacytoid Dendritic Cell Neoplasm?
Blastic plasmacytoid dendritic cell neoplasm, often shortened to BPDCN, is a rare type of blood cancer (a disease where abnormal blood cells grow uncontrollably). This cancer develops from special cells called plasmacytoid dendritic cells, which normally help the body’s immune system fight infections. In BPDCN, these cells become abnormal and multiply out of control.[1]
The disease is quite uncommon. It makes up only about 0.44% of all blood cancers, with an estimated 500 to 1,000 new cases each year in the United States.[2][4] Because it is so rare, many doctors may never see a case during their career, which can sometimes make diagnosis challenging.[13]
The name of this disease has changed several times over the past few decades as doctors learned more about it. It was previously called by different names including “acute agranular CD4+ natural killer cell leukemia” and “CD4+CD56+ hematodermic tumor.” In 2008, the World Health Organization gave it its current name to better reflect what scientists had learned about where the cancer cells come from. In 2016, it was placed in its own category within blood cancers.[1][4]
Who Gets This Disease?
BPDCN can affect people of any age, from newborn babies to elderly adults. However, it is most common in older people, particularly those between ages 60 and 80. The typical age at diagnosis is around 65 years.[3][4]
The disease affects men much more often than women. In adults, about 75% of cases occur in men, giving a ratio of roughly 4 men to every 1 woman. In children, the disease affects boys and girls equally.[2][4]
In children, BPDCN appears to be less aggressive than in adults, though children often have more widespread disease when first diagnosed. The good news is that children generally respond better to treatment than adults.[3]
No specific environmental factors or genetic conditions are known to cause BPDCN. However, in 10% to 20% of cases, people have a history of other blood disorders before developing BPDCN, such as myelodysplastic syndrome (a condition where bone marrow doesn’t make enough healthy blood cells), chronic myeloid leukemia, or acute myeloid leukemia.[1]
How the Disease Shows Itself
BPDCN most commonly first appears as skin problems. Between 61% and 90% of people with BPDCN develop skin lesions as their first symptom. These can appear as nodules, tumors, red or purple patches that look like bruises, raised bumps, or even open sores. The lesions most often appear on the head, face, and upper body, though they can develop anywhere on the skin.[4][7]
The skin lesions occur because abnormal cancer cells invade the skin tissue. These lesions are often deep purple in color, and people frequently develop multiple spots.[2]
Beyond skin changes, people with BPDCN may experience several other symptoms. About half of patients have swollen lymph nodes, usually in the neck, caused by cancer cells building up in these areas. Some people notice their liver or spleen becoming enlarged. General symptoms like tiredness and unexplained weight loss are also common.[4]
In more advanced cases, the cancer spreads to the bone marrow, where blood cells are made. This can lead to problems like anemia (low red blood cell count causing tiredness), low platelet counts (increasing bleeding risk), and low white blood cell counts (reducing ability to fight infections). About 40% of patients have cancer cells circulating in their blood when diagnosed.[4]
The cancer can also affect the central nervous system, including the brain and spinal cord. This is particularly common in children, occurring in about 47% of childhood cases. In more severe situations, the disease may spread to other organs including the breasts, eyes, kidneys, lungs, digestive tract, bones, sinuses, ears, or testes.[4]
How Doctors Identify the Disease
Because BPDCN often looks like other skin conditions or blood cancers, getting the right diagnosis requires careful testing. A biopsy is essential—this means taking a small sample of affected tissue, usually from a skin lesion, to examine under a microscope.[1]
The definitive diagnosis of BPDCN relies on special laboratory tests called immunohistochemistry and flow cytometry. These tests look for specific markers on the surface of the cancer cells. BPDCN cells typically show a characteristic pattern: they are positive for markers called CD4, CD56, and CD123, while being negative for markers found on other types of blood cells.[7]
One particularly important marker is CD123, which is found on nearly all BPDCN tumors. This marker is so consistent that it must be present for doctors to make a diagnosis of BPDCN.[13]
Beyond the tissue biopsy, doctors will typically perform additional tests to understand how far the disease has spread. These may include blood tests to look for cancer cells in the bloodstream, a bone marrow biopsy to check if the bone marrow is affected, and a spinal tap to see if the disease has reached the central nervous system.[4]
Genetic testing of the cancer cells is also becoming more common. Chromosomal abnormalities are frequently found in BPDCN, and understanding these changes can help doctors plan treatment.[7]
Treatment Approaches
Because BPDCN is so rare, there has historically been no single standard treatment approach. Different types of chemotherapy regimens borrowed from treatments for other blood cancers have been tried, including those used for acute myeloid leukemia, acute lymphoblastic leukemia, and myelodysplastic syndrome.[7]
While many patients initially respond to chemotherapy, the disease unfortunately tends to come back, and when it does, it is often more resistant to treatment. This pattern of relapse has made BPDCN particularly challenging to treat.[4]
Stem Cell Transplantation
For patients who are healthy enough to tolerate it, allogeneic stem cell transplantation (receiving stem cells from a donor) offers the best chance for long-term remission and possible cure. Studies have shown that patients who undergo this procedure while in their first remission have much better outcomes. In one study, patients who received a transplant in first remission had a five-year survival rate of 80%.[13]
However, stem cell transplantation is an intensive procedure with significant risks, and not all patients are candidates for it. Older patients or those with other health problems may not be able to undergo this treatment safely.[7]
Targeted Therapy
A major breakthrough came with the development of tagraxofusp-erzs, a medication that specifically targets the CD123 marker found on BPDCN cells. This drug combines a toxin with a molecule that binds to CD123, allowing it to deliver the toxin directly to cancer cells while largely sparing normal cells.[7][8]
In clinical trials, tagraxofusp-erzs has shown considerable promise, with many patients achieving remission. This medication represents an important new option, particularly for older patients who cannot tolerate intensive chemotherapy or stem cell transplantation.[7]
Treatment for Children
Children with BPDCN are often treated differently than adults. Most children can be successfully treated with intensive chemotherapy regimens similar to those used for high-risk acute lymphoblastic leukemia, without necessarily requiring a stem cell transplant. However, transplantation is recommended for children with high-risk features or those whose disease comes back.[3]
Emerging Therapies
Researchers are actively investigating new treatment approaches for BPDCN. These include different types of immunotherapy that help the body’s immune system fight the cancer, as well as targeted therapies that attack specific weaknesses in cancer cells. Clinical trials are exploring these options for both newly diagnosed patients and those whose disease has returned.[3]
What to Expect
BPDCN is an aggressive disease, and historically, outcomes have been poor. Without stem cell transplantation, the average survival time has been about 1 to 1.5 years. The five-year survival rate has traditionally been quite low.[7]
However, these statistics are improving with newer treatments. Patients who can undergo allogeneic stem cell transplantation while in remission have much better outcomes, with some studies showing five-year survival rates as high as 40% to 80%, depending on the specific circumstances.[13]
The introduction of targeted therapies like tagraxofusp-erzs is also changing the outlook for patients, particularly those who are not candidates for stem cell transplantation. Early results with this medication have been encouraging.[8]
Several factors can influence how well a patient does. Younger patients generally have better outcomes than older ones. Patients who achieve a complete remission with initial treatment and then proceed to stem cell transplantation have the best chance of long-term survival. Unfortunately, when the disease comes back after initial treatment, it is often more difficult to control.[4]
It’s important to note that about 10% to 20% of people with BPDCN may also develop other blood cancers, particularly acute myeloid leukemia, which can complicate treatment and affect outcomes.[1]
Despite the challenges, ongoing research continues to improve understanding of BPDCN and develop new treatment options. Patients with this disease should be cared for by specialists experienced in treating rare blood cancers, ideally at centers with expertise in BPDCN.[2]
