Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare form of lymphoma. Lymphoma is a blood cancer in which infection-fighting white blood cells called lymphocytes develop abnormally, crowding out healthy cells. Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) are the two primary categories of lymphoma. Both HL and NHL are cancers of the lymphatic system, part of the body’s immune system that protects the body by removing bacteria, waste matter, and excess fluids from old or damaged cells.
There are two types of lymphocytes, or lymphoid cells: T lymphocytes (T cells) and B lymphocytes (B cells). Lymphatic cancers, known as lymphomas, can develop in either T cells or B cells.
Subcutaneous panniculitis-like T-cell lymphoma is a subcategory of cutaneous T-cell lymphomas. Lymphomas of the skin may also begin in B cells — these are known as cutaneous B-cell lymphomas. Most cutaneous lymphomas develop in lymphocytes in the dermis, a middle layer of the skin.
Subcutaneous lymphomas occur in the adipose (fatty) tissue underneath the skin. Subcutaneous panniculitis-like T-cell lymphoma tends to be primarily cutaneous, meaning it affects only the skin and no other body parts at the time of diagnosis.
As its name suggests, subcutaneous panniculitis-like T-cell lymphoma often looks like another condition: panniculitis, an inflammation of fat beneath the skin. Conditions like septal panniculitis and lobular panniculitis are characterized by painful nodules (solid bumps under the skin) that cause inflammation in the fatty tissue.
SPTCL, however, is caused by infiltration of the subcutaneous tissue by abnormal cytotoxic T-cells that mimic panniculitis. Clinical features of SPTCL include these cytotoxic T cells and preferential involvement of subcutaneous tissue.
SPTCL is an extremely rare form of cancer, making up less than 1 percent of all non-Hodgkin lymphoma diagnoses. Only a few case reports on the condition exist, as well as a few studies specific to it. In fact, SPTCL wasn’t described by researchers until 1991 and wasn’t defined as a distinct entity by the World Health Organization (WHO) until 2001.
SPTCL has only recently been differentiated from gamma/delta T-cell lymphoma, a more aggressive cancer with a similar presentation. Research into the condition is ongoing as scientists work to determine how SPTCL is different from other cutaneous lymphomas.
About 20 percent of the time, subcutaneous panniculitis-like T-cell lymphoma is connected to an autoimmune condition. SPTCL often shows up alongside lupus, though researchers do not yet know how the two conditions are connected or whether one can cause the other.
Some people diagnosed with subcutaneous panniculitis-like T-cell lymphoma have hemophagocytic syndrome (HPS) — overwhelming inflammation due to a severe immune reaction. This reaction is tied to the Epstein-Barr virus (the virus responsible for mononucleosis), which can also play a role in some autoimmune diseases. Research into connections between this virus and SPTCL is ongoing.
Subcutaneous panniculitis-like T-cell lymphoma is more likely to occur in younger adults and also appears to be slightly more prevalent in women, though actual case numbers are so small that it is impossible to know whether this is just a statistical anomaly.
MyLymphomaTeam spoke to dermatologist Dr. Kimberly Bohjanen, a professor of dermatology at the University of Minnesota Medical School with a specialty in cutaneous lymphomas. Dr. Bohjanen noted that symptoms of cutaneous lymphomas are unlike those of more common skin cancers. “They’re not usually a bleeding spot or a changing mole,” she explained. “It's more of a rash usually, that just doesn't go away, that persists over time, and that won't usually respond to the standard treatments.”
The primary symptom of subcutaneous panniculitis-like T-cell lymphoma is a series of nodules under the skin. Because they form in the subcutaneous tissue, these nodules may feel like they are deep under the skin. Few people report that these nodules are painful.
SPTCL nodules may seem to appear and disappear at random, especially in the early stages of the condition. As SPTCL progresses, the nodules may linger for a longer time or appear over multiple areas of the body simultaneously. These subcutaneous nodules don’t respond to standard topical skin treatments, and they return with persistence.Subcutaneous nodules can form on the arms, legs, or trunk of the body. They are small — between half a centimeter and 2 centimeters in diameter — and may come and go. Subcutaneous nodules are unlikely to break open, or ulcerate, though this is possible on rare occasions.
Approximately 50 percent of people diagnosed with SPTCL also experience systemic signs and symptoms, which include:
Because subcutaneous panniculitis-like T-cell lymphoma can look like other conditions (such as eczema, dermatitis, and cellulitis), it can take months or years to diagnose it accurately. A differential diagnosis — one that rules out other causes — can help determine whether your symptoms are caused by SPTCL or another commonly confused condition, like lupus erythematosus panniculitis (also referred to as lupus profundus).
SPTCL is a slow-growing (indolent) cancer. Because subcutaneous nodules can come and go, treatments may appear to have worked when they actually haven’t. It is generally the reappearance and persistence of the nodules that indicate to a doctor that something else is going on beyond a common skin condition. Some people diagnosed with SPTCL visit a number of dermatology offices before they receive the correct diagnosis.
A punch biopsy, the removal of a section of a subcutaneous nodule performed under local anesthesia, is usually required to diagnose SPTCL. Because of the rarity and inconsistency of the disease, as well as its ability to appear like other conditions, it may take several biopsies to accurately diagnose SPTCL.
The punch biopsy will be examined by a skin pathologist who studies tissues under a microscope. They will stain the slide to show the difference between B cells and T cells and examine samples of the surrounding fatty tissue to look for abnormalities.
Diagnosis of SPTCL may also include some procedures commonly used to diagnose non-Hodgkin lymphoma. Your doctor will use the combined results of these tests and exams to make a diagnosis.
A doctor will examine your skin to look for signs of subcutaneous nodules. They may also look for other symptoms of lymphoma and ask whether you have experienced systemic symptoms, such as unexplained fevers, chills, and unintended weight loss.
Performed by a dermatology professional, this exam will attempt to determine whether the subcutaneous nodules have a cause other than lymphoma. This may include disease-specific pathologic, immunophenotypic, and T-cell receptor tests of a skin biopsy.
Doctors may take a sample of your bone marrow (the soft, living tissue inside your bones that produces red blood cells) and examine it under a microscope to check for lymphoma cells.
Your doctor may examine your nodules and fatty tissue cells using a computerized tomography (CT) scan, magnetic resonance imaging (MRI), or ultrasound technology. They may also perform a positron emission tomography (PET) scan to look for nodules in other locations on your body.
Your doctor may look at liver function tests to determine your levels of enzymes and red blood cells, while also searching for cytopenia (low blood cell count). In addition, they may choose to test for the presence of lymphoma cells.
Because SPTCL often occurs alongside lupus,your doctor may look for signs of an autoimmune disorder.
When SPTCL is diagnosed, your doctor will do their best to stage the cancer by checking whether the lymph nodes are affected. Staging describes how advanced a case of cancer is. Dr. Bohjanen noted that staging is a key part of the diagnostic process, because different stages of cancer may respond differently to treatments.
Because SPTCL is so rare, however, it may be difficult to stage — researchers do not yet fully understand the clinical course of the condition. Your medical team will do their best to accurately stage the cancer and determine the right course of treatment.
Treatment options for subcutaneous panniculitis-like T-cell lymphoma can vary based on the symptoms you’re experiencing and the specific locations of your nodules. Given the rarity of the condition, treatments for SPTCL have not yet been standardized.
Corticosteroids and immunosuppressants play an important part in the treatment of SPTCL. These serve to dial down the immune response that seems to play a part in the progression of the disease. These are often given alongside chemotherapy, especially when the condition is progressing. Some of these medications may include:
Radiation therapy may also be used to treat SPTCL. This is particularly useful in helping to achieve long-term remission. It may also help those diagnosed with SPTCL to experience rapid improvement if their nodules are causing problems or discomfort in a localized area. Chemotherapy is sometimes used in progressive cases of SPTC.
Another option for treating SPTCL is surgery to remove nodules that cause discomfort or that are deep in subcutaneous tissue. However, this is uncommon, as the nodules usually disappear on their own when the condition is treated effectively.
Finally, stem cell transplants have shown promise in improving SPTCL when the condition is not responding to other treatments or when the cancer has spread beyond the skin. Research into this treatment is still ongoing, but it may be possible to participate in a clinical trial testing stem cell transplantation.
Clinical trials for SPTCL are ongoing. Participating in clinical trials can help those living with the condition access new and promising treatment methods they may not otherwise receive. Your health care providers should be up to date on the trials available, and they can submit your case for trails you are eligible for and interested in.
Dr. Bohjanen noted that most cases of cutaneous lymphomas are caught in the early stages, so people have a chance to get the treatment they need before the cancer progresses very far. The prognosis for people diagnosed with subcutaneous panniculitis-like T-cell lymphoma is generally positive, with overall five-year survival rates between 85 percent and 91 percent for those with primary cutaneous forms of the condition.
An important prognostic factor is the presence or absence of hemophagocytic syndrome. Between 15 percent and 20 percent of those diagnosed with SPTCL go on to develop HPS. The five-year survival rate for SPTCL complicated by HPS is 46 percent.
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