Skin diseases are all too common in clinical practice and can be caused by allergies, scratching, genetics, immunity, and other factors. In general, most skin diseases can be treated and cured early because they are easily detected. However, there is a kind of skin disease that not only has a large lesion area and easily affects the external appearance, but also has a long course, persistent and recurring disease, making people extremely distressed! It is the “undying cancer” – psoriasis.
Psoriasis is an immune-mediated polygenic genetic skin disease that can involve the entire body of the skin in severe cases, and has a very high incidence, affecting about 120 million people worldwide. The most frightening thing is that psoriasis not only affects the appearance of patients, but also may increase the probability of malignant neoplastic diseases, such as skin tumors and lymphomas.
1, psoriasis and skin tumor, it turns out to be so closely related!
Psoriasis and skin tumors are both common clinical diseases, and psoriasis may increase the probability of skin tumors or lead to the occurrence of skin tumors.
It is clinically believed to be related to genetic, immune, and various environmental factors, with specific mechanisms involving abnormal cell differentiation and proliferation, cell adhesion molecules, and other aspects.
(1) Abnormal differentiation and proliferation of keratin-forming cells
Psoriasis is a common clinical inflammatory and refractory skin disease, while in terms of molecular mechanisms, chronic inflammation has the potential to contribute to the formation of tumor cells, which means that psoriasis may turn into skin tumors, such as squamous carcinoma.
Both of them show abnormal proliferation of epidermal keratin-forming cells, and there is an increased expression and abnormal distribution of epidermal growth factor receptors.
(2) Cell adhesion molecules
Cell adhesion molecules play an important role in the pathogenesis of psoriasis and tumors, such as intracellular adhesion molecule-1, which can regulate the migration of T lymphocytes to the epidermis and dermis, and its ability to promote the binding of keratinocytes-lymphocytes and induce the formation of psoriatic lesions. Meanwhile, tumor necrosis factor and interferon-gamma can also regulate the expression of intracellular adhesion molecule-1.
In addition, relevant in vivo and in vitro experiments have also confirmed that high expression of the small-molecule calcium-binding protein S100A7 can inhibit epidermal hyperdifferentiation and tumor growth and invasion in early stages of psoriasis and squamous carcinoma, and that downregulation of S100A7 expression can also stimulate tumor growth and invasion by activating enhanced β-catenin signaling in late stages of the disease.
However, although psoriasis and skin tumors share abnormal differentiation and proliferation of cells, how the benign cell proliferation in psoriasis is transformed into malignant cell proliferation and differentiation, which leads to skin tumorigenesis, is still not fully understood and needs to be further explored.
According to its common pathogenesis, clinical treatment with anti-TNF-α drugs has temporarily achieved better results, such as infliximab, adalimumab and Yicep. These drugs are relatively safe for psoriasis patients with a history of skin tumors, but the safety of methotrexate, a drug commonly used in psoriasis, still needs to be verified.
After talking about skin tumors, let’s talk about lymphoma next.
2, psoriasis and lymphoma, how far away is it?
Lymphoma is a group of malignant tumors originating from lymph nodes or other lymphoid tissues, divided into Hodgkin’s disease and non-Hodgkin’s lymphoma. Its development seriously affects the normal mechanism of lymphocytes and the immune system, and related studies have found that patients with psoriasis have an increased risk of developing lymphoma compared to the general population.
A survey on the prevalence, incidence and risk of cancer in patients with psoriasis and psoriatic arthritis showed that the prevalence of lymphoma in patients with psoriasis was 0.25%, with a lower prevalence of non-Hodgkin’s lymphoma at 0.30%.
This may be related to the overactive immune system in patients with psoriasis, which leads to more frequent growth and division of lymphocytes than normal, thus increasing the risk of lymphoma development.
Regarding the treatment of patients with psoriatic co-morbid lymphoma, methotrexate and cyclosporine, have not been found to be associated with an increased risk of developing malignancies such as lymphoma, but at the same time, because patients suffering from malignancies such as lymphoma are usually not involved in clinical trials, it is not possible to clarify the specific clinical risk and it is not recommended to apply such inhibitors in patients with psoriatic co-morbidities with malignancies.
As for the TNF-α inhibitors, immunomodulatory therapy and non-immunosuppressive therapy commonly used for psoriasis, they have little effect on the recurrence of systemic malignancies, and are not absolutely contraindicated for psoriasis patients with malignancies, and the safety of treatment can be ensured through regular follow-up and disease monitoring.
Psoriasis is by no means only a skin problem, but also a systemic inflammatory disease, which will have certain effects on the physical function, psychological and social aspects of the patient. It is recommended that psoriasis actively cooperate with the physician in assessing the risk of co-morbidities based on the awareness of their condition.
References
[1]Zhao X,Li B. Study on the pathogenesis of psoriasis and skin tumors [J]. Journal of Liaoning University of Traditional Chinese Medicine,2011,13(03):96-98.
[2]Zhang L., Li Y., Li Y. Z.. Psoriasis and its treatment-related risk of tumor development[J]. Medical Review,2018,15(24):2980-2983.