Podoconiosis - Causes, Clinical Features, Diagnosis, and Management

Introduction

Podoconiosis is a type of lymphedema that mainly affects farmers in tropical highland regions. It is also referred to as endemic non-filarial elephantiasis and is one of the NTDs (neglected tropical diseases) recognized by the WHO (World Health Organization). Lymphedema refers to swelling in one or more body parts due to improper lymphatic system functioning. Podoconiosis is a type of lymphedema in which the lower limbs are affected and mostly occurs in individuals with chronic exposure to irritant volcanic clay red soil.

Podoconiosis has some clinical features similar to lymphatic filariasis and is often misdiagnosed. Podoconiosis is more prevalent in remote, poor, and underprivileged regions, mainly in African countries. It mainly affects those who walk barefoot, resulting in physical impairments and an inability to work, worsening marginalized regions' economic and social conditions. The condition can be prevented by encouraging the use of appropriate footwear.

What Are the Causes of Podoconiosis?

The pathophysiology of podoconiosis depends on various factors like host susceptibility, favorable environmental factors, and poverty-related circumstances.

• Absorption of colloid-sized soil particles through cracks or pores on the foot sole.

• Absorption can occur either through minor injuries during hoeing or digging manually or through sweat ducts on the foot sole.

• These particles are then taken up by phagosomes present in macrophages on lower limb lymphatics. This results in inflammatory reactions that cause subendothelial edema and fibrosis.

• The vessels enlarge and stiffen, resulting in vascular dysfunction.

• Dermis and sub-dermis get attached to the deep fascia.

• Lymphatic vessels get narrowed and obliterated.

• Sweat glands, sebaceous glands, and hair follicles get destroyed.

What Are the Clinical Features of Podoconiosis?

• Bilateral asymmetric swelling of the legs. The swelling is progressive and mostly confined to the region below the knee. The condition presents with ascending lymphedema in which the swelling first appears on the feet, then spreads proximally, and may reach the groin.

• The condition has a prodromal phase and a later phase. The prodromal phase begins during early childhood or adolescence and presents with the following:

  • Burning sensation in the lower leg or feet.

  • Itching of the dorsum of the forefoot.

  • The medial toes show mild swelling.

• The latter phase starts during a period of intense activity, during the start of the menstrual cycle, or at night. This episode affects the same limb and presents with:

  • Mild fever that usually subsides in a few days.

  • Femoral lymph nodes become tender.

• Persistent itching can lead to repeated scratching and cracks in the skin. This can lead to secondary bacterial infections, like cellulitis.

• The early signs include:

  • The forefoot gets widened due to mild swelling, and the toes get separated (splaying of the forefoot).

  • Toes lack normal curvature and appear like lifeless sausages (block toes).

  • Hyperkeratosis (thickening of outer skin layer)

  • Increased skin markings.

  • Plantar edema (fluid accumulation below the skin on the foot sole).

  • Slight lymphatic oozing into the skin.

• The disease progresses and reaches a chronic, irreversible stage, which presents with:

  • More than one hardened skin nodule.

  • The limbs appear thickened, leathery, and fibrotic. Initially, the swelling was ‘water bag’ type, which is soft and fluid and becomes leathery and fibrotic in the advanced stage.

• The condition consists of five stages:

  • Stage 1 - Reversible edema or swelling.

  • Stage 2 - Swelling is below the knee and not completely reversible overnight.

  • Stage 3 - Swelling is below the knee and not completely reversible overnight, and lumps or knobs are present above the ankle.

  • Stage 4 - Swelling is below the knee and not completely reversible overnight, and lumps or knobs are present at any location.

  • Stage 5 - Joint fixation.

How Is Podoconiosis Diagnosed?

The diagnosis of podoconiosis is based on typical clinical features. The geographical context is also taken into consideration. The diagnosis is based on proper patient history and typical clinical features and excludes other conditions that cause lymphadenitis.

What Is the Differential Diagnosis of Podoconiosis?

The differential diagnosis includes all those other conditions that result in elephantiasis:

• Lymphatic Filariasis - In this condition, the edema (swelling) first appears in the groin region and then spreads downward. The condition is unilateral and usually stops above the knees.

• Mycetoma - It is a chronic skin infection that can affect the bones, muscles, tendons, and joints.

• Endemic Kaposi Sarcoma - A condition that affects the endothelial cells of the lymphatic system and the blood vessels. The condition presents as lymphedema and flat patches on the lower legs.

• Lymphedema Due to Leprosy - The condition presents with loss of sensation on the heels, but sensation is present on the toes and forefoot.

• Chronic Recurrent Erysipelas - A potentially serious bacterial skin infection affecting the upper dermis.

What Are the Complications of Podoconiosis?

The complications of podoconiosis are:

• Secondary bacterial infections.

• Loss of ability to work due to physical impairment.

• Social isolation.

• Reduced quality of life.

• Psychological morbidity.

• The prevalence of depression was common among the affected.

What Are the Treatment Options of Podoconiosis?

Podoconiosis is a preventable condition that can be avoided by using proper footwear and using hard floor covering at houses by susceptible individuals.

In the case of an established disease, the following measures are taken:

• Maintenance of proper foot hygiene.

• For daily washing and cleaning of the affected skin, the affected person should be provided access to clean water, antiseptics, and soap.

• Using emollients aids in maintaining the integrity of the skin barrier and prevents skin fissures and the entry of harmful microbes and particles.

• Compression bandaging.

• Covered footwear.

• Relocation of living environment.

• Manual lymph drainage.

• Foot and calf exercises.

In severe cases:

• Elevating the limbs for at least 18 hours per day.

• Compression bandage.

Surgical intervention has been attempted. Surgical tissue excision followed by skin grafting was found to be unsuccessful as scar tissue aggravated the symptoms. Shave excision of the hard nodules with the secondary intention of healing, in which the surgical wounds are left to heal independently.

Conclusion

Podoconiosis is a debilitating, chronic, and neglected disease that affects those continuously exposed to irritant volcanic clay red soil. The condition may result in physical impairment and can negatively impact the affecter's mental health and quality of life. But it is a condition with a huge potential for elimination and can be prevented by using appropriate footwear and good hygiene practices right from childhood.