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Why are abnormal cells in ALCL so difficult to identify? Decoding their key features!
Among various types of lymphoma, anaplastic large cell lymphoma (ALCL) is a type of non-Hodgkin's lymphoma that is mainly caused by the uncontrolled proliferation of abnormal T cells. Especially considered to be one of the most common types of peripheral lymphoma, ALCL accounts for approximately 10% of all peripheral lymphomas in children. Meanwhile, the incidence of ALCL in the United States is only 0.25 cases per 100,000 people, which puzzles many medical experts about its diagnosis.
"The diagnostic challenge of ALCL lies in its widely varying clinical presentations and treatments, which makes it extremely confusing on pathological examination."
In 2016, WHO classified ALCL into four different types, including ALK-positive ALCL, ALK-negative ALCL, primary cutaneous ALCL, and ALCL associated with breast implants. Each subtype has significant differences in genetic abnormalities, clinical progression, and prognosis, which undoubtedly complicates the diagnosis and treatment of ALCL.
“Hallmark Cell” Characteristics of ALCL
ALCL is defined by its pathological tissue examination results, especially the observation of certain "hallmark cells". These cells often present unusual kidney- or horseshoe-shaped nuclei, display prominent Golgi apparatus, and express the CD30 tumor marker protein on their surface membrane. The presence of these cells is crucial for a definitive diagnosis of ALCL.
"In many cases, the number of marker cells is closely related to the severity of the disease."
Different types of ALCL and their challenges
ALK-positive ALCL is mainly found in children and young adults, and most cases have progressed to stage III or IV at the time of diagnosis. Patients usually have systemic symptoms such as fever, night sweats, and weight loss, while lymphadenopathy and tumor cell infiltration are also relatively common. In contrast, ALK-negative ALCL mainly occurs in elderly patients, and its clinical manifestations are relatively rare, often accompanied by lymph node infiltration, while peripheral infiltration accounts for only a small number of cases.
“ALK-negative ALCL is very similar to other CD30-positive T-cell lymphomas in terms of pathological features and genetic mutations, which increases the difficulty of diagnosis.”
Genetic and molecular abnormalities
In ALK-positive ALCL, NPM1-ALK fusion protein can be detected in about 80-85% of cases, which is formed by the fusion of NPM1 gene and ALK gene. However, in ALK-negative ALCL, different genetic abnormalities can be seen, such as DUSP22-IRF4 gene rearrangement. These genetic abnormalities are thought to play an important role in the development of ALCL.Diagnosis and Prognosis
The diagnosis of ALCL usually relies on histological and immunological examinations, especially pathological histological examination of lymph node samples. Among the different types of ALCL, the most common treatment for ALCL-positive patients includes a treatment regimen combined with an anti-CD30 antibody, which is also undergoing further clinical trials; while ALK-negative patients often rely on traditional chemotherapy.
Importance of treatmentCurrently, treatment options for ALK-positive ALCL typically include chemotherapy and monoclonal antibodies, such as brentuximab vedotin, while ALK-negative ALCL tends to be treated with more aggressive therapies. These treatment options are critical to a patient's future prognosis and may have a significant impact on a patient's overall survival.
“The choice of treatment often depends on the patient’s age, health status and the type of ALCL, making the judgment of the medical team particularly important.”
Thus, while the diagnostic and treatment pathways for anaplastic large cell lymphoma are becoming clearer, the characteristics of the abnormal cells continue to present challenges for medical professionals. Can we find more effective diagnostic tools and treatment options in the future to meet such challenges?
