Introduction

Degos disease, also referred to as Malignant Atrophic Papulosis,¹ is a rare condition that seemingly affects small and medium-sized blood vessels regardless of age or sex. However, young middle-aged adults have been shown to be more susceptible to the disease. The severity of the disorder is mainly dependent on the site of infection, which is usually on the skin, but could also show up near the genital areas or even affect internal organs and the nervous system.

Common symptoms usually include small red or white papules with a central depression or scab, and mild to moderate itchiness similar to that of rashes. The two main concerns caused by the disorders are usually necrosis²⁵ and thrombosis,²⁶ or commonly known as tissue death and blood clotting, respectively. The current variety of modern treatment utilises classes of drugs that prevent thrombosis in blood vessels and hence stop tissue damage and necrosis if left untreated in the long run.

Mechanism of action

Degos disease is a unique condition that has two distinct but closely related mechanisms. Studies conducted by various researchers have concluded that the possible pathophysiology pathway is vasculitis² or coagulapathy³ from some form of endothelial cell dysfunction.

The immune system’s role

Our immune system consists of two main categories of white blood cells: innate cells, which act rapidly and provide short-term defence, and adaptive cells, which respond more slowly but offer long-term, targeted immunity. Vasculitis, an autoimmune disease, is proposed to be the primary mechanism, where white blood cells within our body attack the blood vessels, leading to inflammation.² A specific adaptive immune cell, CD8⁺ cytotoxic T lymphocytes,⁴ has been associated with malignant atrophic papulosis, where the white blood cell becomes abnormally aggressive towards endothelial cells for antigens presented on their surface.

In a healthy immune system, T cell activation only occurs when another group of cells called antigen-presenting cells (APC) bind to the T cell while expressing the antigens they obtained from a pathogen. This process requires two signals, a primary antigen recognition and secondary co-stimulatory signalling, simultaneously to elevate intracellular calcium ion concentration. The action allows an enzyme²² called calcineurin to induce a specific gene that encodes for a growth factor named interleukin 2⁶ (il-2). Only through IL-2 T helper cells become active and stimulate the rapid expansion and activation of CD8⁺ cytotoxic T cells, enabling them to target and destroy abnormal or infected cells.

Coagulopathy pathophysiology

It is suspected that the potential damage driven by the white blood cell on the endothelial wall is also involved in the coagulopathy afterwards, as this lesion,²³ a region of damaged tissue, disrupts the concentration of important chemical mediators in the blood vessels. Under normal conditions, blood vessels and endothelial cells maintain a certain balance of nitric oxide and prostacyclin¹² concentration. When the equilibrium of these two effector molecules is disrupted, due to trauma on the endothelial cell, a signalling cascade is initiated in which platelets play a key role in the early stages of repair. Prostacyclin normally binds to platelet receptors²⁴ to inhibit their activation, while nitric oxide promotes vasodilation. A reduction in prostacyclin levels removes this inhibitory effect, allowing platelets to become activated and release additional chemical mediators such as ADP, thromboxane A₂, and serotonin, which further promote platelet aggregation and vascular changes.

Platelets by themselves are unable to create a full-fledged clot; it requires additional factors to assist them in stopping the bleeding. Depending on whether the trauma caused by degos disease is intrinsic or extrinsic, certain specialised cascade pathway factors become stimulated. Direct damage to blood vessels stimulates the intrinsic pathway, in which a series of clotting factors are sequentially activated. Similarly, trauma to the vascular wall via external forces activates the extrinsic pathway, and a different set of clotting factors is activated. However, both pathways ultimately converge at the common pathway, where factor X plays a central role by converting prothrombin into thrombin. Thrombin then converts soluble fibrinogen into insoluble fibrin, forming the stable clot.

Hence, the proposed theory on how degos disease functions indirectly promotes platelet activation, leading to thrombosis, an excessive blood coagulation in a localised area.

Treatment 

Anticoagulant drugs

As described above, due to the severe coagulopathy associated with the degos disease, current treatment commonly includes anticoagulant remedies. Most agents in this class exert their effects by targeting specific clotting factors within the intrinsic, extrinsic, or common pathways, thereby reducing thrombus formation and improving blood flow.

Common agents

• Indirect thrombin inhibitors

The most widely used treatments under this classification are heparin⁸ and its modified version, low-molecular weight heparin¹³ (LMWH). These agents work by binding to and enhancing the activity of our body’s natural anticoagulant, antithrombin III. Once activated, antithrombin III inhibits activated factor X³ (factor Xa) and thrombin (factor IIa), accelerating the suppression of clot formation.

LMWH, like dalteparin, has a higher selectivity for inhibiting factor Xa than thrombin, making it useful for targeted anticoagulation compared to normal heparin. Fondaparinux is a synthetic anticoagulant that selectively inhibits factor Xa without binding to plasma proteins, reducing variability in drug response.

• Direct inhibitor

Other popular medications, for instance, rivaroxaban¹⁹ and edoxaban²⁰ are preferred over heparin as it can be taken orally rather than requiring intravenous administration. These direct oral anticoagulants⁸ (DOACs) are absorbed into the bloodstream and directly inhibit factor Xa without relying on antithrombin III. Unlike heparin, they act without intermediary plasma protein activation.

• Vitamin K inhibitors

Warfarin,⁸ one of the first anticoagulants discovered alongside heparin, is an example that falls under vitamin K inhibitors. Vitamin K is responsible for the synthesis of important chemical mediators like prothrombin, factor X, and others. In its reduced form, vitamin K serves as a cofactor for the carboxylation of precursor clotting proteins, a step required for their activation. However, when warfarin is present, vitamin K epoxide reductase, the enzyme responsible for converting oxidised vitamin K back into its reduced form, is inhibited, thereby preventing the synthesis of active clotting factors.

Risks & limitations 

Unfortunately, the major risk associated with anticoagulants includes bleeding but also heparin-induced thrombocytopenia (HIT), a severe condition in which the immune system rapidly produces antibodies complementary to heparin, leading to unwanted clot formation and decreased platelet count. Fortunately, protamine sulfate¹⁰ exposure can help to inhibit heparin and its variation by forming a stable inactive complex. 

In addition, certain anticoagulants like warfarin are known for their numerous side effects and extensive drug-drug interactions, which could limit their effectiveness and impose restrictions on our dietary freedoms. However, it can also be argued that warfarin’s long history of clinical use and well-understood pharmacology make it comparatively safer to dose than some newer anticoagulants, whose long-term effects are less fully established.

Antiplatelet therapy

Antiplatelets are a specialised group of molecules, like anticoagulants, which reduce abnormal blood clotting. The main difference between the two sets of drugs lies in their pharmacological site of action. While anticoagulants work on various clotting factors in the coagulation pathways, Antiplatelet medications, indicated by their names, act directly on platelets, binding and blocking receptors or proteins involved in platelet activation and aggregation. 

As this class of drug can address vascular occlusion in skin and organs, it treats the surface symptoms raised from the disease. Below are key examples of platelet aggregation inhibitors, along with their mechanisms, benefits, and limitations.

Common agents used

• Enzyme COX-1 inhibitor

Aspirin can irreversibly bind to an enzyme, a complex 3D protein structure translated¹¹ or built from our DNA sequence, within platelets called cyclooxygenase-1(COX-1). COX-1 synthesises prostaglandin H2 from arachidonic acid, which forms thromboxane A2, the chemical mediator that causes clot formation.

• Glycoprotein inhibitors (GPIIb/IIIa)

Specific glycoprotein¹⁸, a carbohydrate protein-linked receptor, GPIIb/IIIa are the location where insoluble fibrinogen binds, and is also a site of target for antiplatelets such as tirofiban, preventing cross-linkage of platelets from strengthening the clotting mesh.

• Phosphodiesterase inhibitors

Cilostazol and dipyridamole are phosphodiesterase inhibitors, an enzyme present within platelets and also vascular walls that regulates vasoconstriction and platelet activation through secondary messengers such as cAMP, Calcium ions, and ADP. The binding of the drug leads to a cascade of signalling that promotes vasodilation and platelet inhibition, which can be caused by the disease.

Risks & limitations

Similar to how anticoagulant drugs function, the use of antiplatelets carries the same significant risk of excessive bleeding at injury sites as a result of platelet inhibition. Furthermore, as the drugs only treat the surface symptoms, they do not directly target the underlying cause of Degos disease. As a result, their role at best may only hinder the progression of the disease.

Immunosuppressants 

Since Degos disease is hypothesised to have immunoinflammatory properties, physicians may prescribe immunosuppressants in patients confirmed to have the condition. As discussed earlier, CD8⁺ T lymphocytes have been implicated in Degos disease pathology; therefore, the therapeutic aim of immunosuppressive therapy is to suppress and reduce immune-mediated damage to the blood vessels.

Common agents

• Corticosteroids 

Corticosteroids¹⁶ are a major subclassification of immunosuppressants and are usually strictly regulated drugs due to their potent systemic effects. Under this class, we have prednisone and its active ingredient, prednisolone, which are highly lipophilic, fat-soluble, enabling them to diffuse across the T cell’s membrane¹⁹ barrier. They exert a genomic effect on the lymphocyte by inhibiting an intracellular receptor that is responsible for controlling various transcription factors¹⁷ that switch on the gene transcription for Interleukin-2.

• Antibodies 

In more recent research, antibodies have also become quite a popular treatment to provide suppression. Monoclonal antibodies like antithymocyte globulin¹⁵ can be produced to bind to antigens on the T-cell directly and programme apoptosis, destruction of the T-cell, or compete with interleukin-2 function via basiliximab. Although they are usually more popular with organ transplantation procedures, as of now.

• Costimulation inhibitors

Belatacept¹⁴ and abatacept are examples of costimulator inhibitors; they function by disrupting the costimulation of secondary interactions with C28 on T cells by inhibiting a receptor site on APC called C80/86. Belatacept is a modulated version of abatacept with improved efficacy and affinity; hence, it is usually a more effective agent in this treatment.

Risks & limitations

With immunosuppression drugs, the more concerning side effect would be, of course, a weakened immune system, which risks opportunistic infections from other pathogenic species or even our own body cells. Since the immune system regulates any harmful substances within our body, shutting it down would also impair cell tumour surveillance. Selectivity with these medications is also more challenging as all variations of lymphocytes require the initial T-helper cells induction. Additionally, like many symptom-targeting treatments, discontinuation often leads to recurrence of vascular lesions.

Summary

At present, degos syndrome has no definitive cure, but there are different procedures and therapies that are able to treat the symptoms caused by the illness. Various drug classes, like antiplatelets and anticoagulants, as discussed above, are able to suppress and treat more severe concerns, such as blood vessel clotting. Moreover, if degos disease is conclusively classified as an autoimmune disorder in the future, a range of immunosuppressant medications could be employed to slow down the disease progression and alleviate symptoms, thereby improving our quality of life.

Looking ahead, it is entirely plausible for future treatments to utilise pharmacogenomics⁷ to develop personalised therapies for you according to your genetic profiles to avoid potential complications. With the constant improvement of various modern medical technologies, perhaps standardised therapeutic protocols for rare diseases like Degos could one day become more accessible, even for the small populations they affect.