What is Dermatomyositis?

 Recently, our dermatology teacher had given us a very interesting task: he had asked us to watch his patients when they were being diagnosed by him, and we had to write down the disease of each patient without touching or performing any diagnostic method. We just had to watch and write down the probable disease or cause. And there we saw a patient with papules on her hand, swelling, and redness around her eyes; she was also unable to lift her hand properly. I thought she may have an infection or something. 

But I was wrong. After the class, our teacher explained her condition. She had dermatomyositis, and he asked us to remember some important diagnostic features of this disease. 

 Lets start the topic, What is Dermatomyositis? 

In this article, i am going to explain Dermatomyositis .And its 

• Cause,
• Agents that can trigger the disease,
• How it develops or progress
• What are the Signs and Symptom we can see 

So, please follow through this blog 

First, lets introduce Dermatomyositis, 

It is an Autoimmune disease, which mainly affect skin and muscle. And it is a chronic inflammatory disorder.

Autoimmune means our own immune system attacks our system and cause inflammation.If you want to know more about our immune system then

How our body protect us from pathogens?

But in this disease, the immune system whose duty is to protect us,attacks its own body, thus cause inflammation. 

Dermatomyositis occurs more commonly in females.

There are mainly two types, on the basis of onset,

1. Adult onset type (peak age of onset is 50 years)
2. Juvenile type (peak age is approx 5-10 years)

1.Cause

The exact cause of Dermatomyositis is still unknown. Till date we can not find, why our own immune system attacks its own system.But there can be some factors,which plays a role in developing this disease i.e Genetic, Immunologic,infectious and environmental factors.

2.Agents that can trigger the disease

Infectious agents have been suggested as possible triggers of Dermatomyositis.  These include

1. Viruses(eg, coxsackievirus,parvovirus,echovirus,human T-cell lymphotropic virus type1[HTLV-1],HIV )
2. Toxoplasma species
3. Borrelia species

There are some medications, which can also be trigger i.e 

• Statins
• Penicillamine
• Anti-tumor necrosis factor drugs
• Anti-programmed cell death drugs
• Cyclophosphamide
• Bacillus Calmette-Guerin(BCG) vaccine
• Quinidine

3.How it develops or progress.

It develops through a complex process , but i will try to make you understand as much as possible. 

First due to any above factor i.e Genetic, Immunologic,infectious and environmental factors, our immune system got activated. It produces antibodies(i.e Anti-Mi-2/Anti-Jo-1) against our Muscle's DNA,provoking a systemic inflammatory response. Due to inflammatory response, Cytokines and Chemokins is released in the blood vessels of muscle.

These cause two things 

1. Perivascular inflammation (Around blood vessels)
2. Capillary necrosis 

So, due to upper reasons, blood supply to the muscle fibers decreases. This lack of blood supply cause endofascicular hypoperfusion and muscle ischemia.

Endofascicular hypoperfusion is a condition where there is reduced blood flow to the endofascicular region of a nerve. This can result in nerve damage and dysfunction, leading to symptoms such as numbness, tingling, weakness, and pain in the affected area.

And Muscle ischemia cause muscle tissue damage.

When these processes occur in the skin of the hands,it form hyperkeratotic flat red papules called Gottron Papules. And when this occurs in  upper and lower eyelids,causing red-purple discoloration/swelling, its called Heliotropic rash. These are some very important signs of Dermatomyositis. 

3.What are the Signs and Symptom we can see 

1.Muscle

Dermatomyositis presents with a varying degree of muscle weakness, like in intial presentation, the muscle involvement is symmetric and proximal but with course of disease, Distal muscle weakness also occurs.

Patients often have difficulty with activities such as rising from a chair, climbing stairs, lifting objects or washing thier hairs.

With progression, when distal muscle got involved, patient faces difficulty in holding and manipulating objects.

When the neck extensor muscle are involved, patients can presen with head drop.With severity patient can develop dysphagia (difficulty in swallowing), dysphonia(difficulty in producing sound) and weakness in the muscle of respiration. 

2.Skin

A hallmark sign of Dermatomyositis are Gottron's papules and Heliotrope rash. We can also see Shawl sign, its erythma (redness) over the upper back,posterior neck,and shoulders, sometimes with extention to the lateral arms.

We also see Vasculopathic lesions, like Livedo reticularis,Ulceration and telangiectasia.

Gottron's papules

Heliotrope rash

Shawl sign

Livedo reticularis

Telangiectasia

3.Lung

Lung dysfunction is a significant source of mortality in patient with Dermatomyositis. It is due to the dysfunction of muscles of respiratory system.

4.Systemic Symptoms 

Fever, Fatigue, Joint pain, Weight loss are some common symptoms associated with Dermatomyositis. 

 

So, this is a brief explanation of Dermatomyositis.  If you have any doubt, please reach me at Contact us page. And please check my other blogs, if you want to learn more.

Thank you