Flegel Disease - Causes, Clinical Features, Diagnosis, and Treatment

Introduction

Flegel disease or hyperkeratosis lenticularis perstans or HLP, was described in 1958 by H.Flegel. Flegel disease or hyperkeratosis lenticularis perstans or HTP, is a rare asymptomatic skin condition affecting the legs and feet. It is familiar with its autosomal dominant inheritance pattern. By definition in the medical dictionary, it is defined as an autosomal dominant skin disorder occurring in the third or fourth decade of life. It is characterized by pink, red, or yellow to brown scaly papules on the lower leg and foot, sometimes on the trunk, thigh, arm, back, palm, or sole. Flagel disease is also known as “hyperkeratosis lenticularis perstans” and HLP.

What Is Flegel Disease?

Flegel disease or hyperkeratosis lenticularis perstans or HLP, is an autosomal dominant inheritance skin disorder characterized by hyperkeratotic papules distributed on the lower extremities. It is reported that females are more susceptible to hyperkeratosis lenticularis perstans (HLP) than males, which usually occurs within 40 to 50 years of age. Flegel disease is rarely associated with endocrine disorders such as diabetic mellitus or hyperthyroidism. Past medical history and systemic examination are important in this condition to get the proper diagnosis.

The general features of Flegel disease, hyperkeratosis lenticularis perstans, or HLP are mentioned below.

• Age: 40 to 50 years of age.

• Sex: Women are more susceptible than men.

• Type: Autosomal dominant.

What Does a Flegel Disease Look Like?

Flegel disease or hyperkeratosis lenticularis perstans (HLP), is characterized by multiple lesions; color ranges from red to brown papules of about 1 to 5 millimeters (mm) showing disc or lens (lenticularis) shape. The affected areas are erythematous, and the patient will experience painful itching. Itching sometimes causes pinpoint bleeding in the scrapping area. The most common areas affected are the dorsal side of the feet, distal extremities, external pinna, palms, soles, and oral mucosa. Diffuse involvement is observed in certain cases. Flagel disease or hyperkeratosis lenticularis perstans (HLP), has localized and unilateral variants. The clinical features of Flegel disease or hyperkeratosis lenticularis perstans, are mentioned below.

• Color: Reddish-brown.

• Size: Papules 1 to 5 mm.

• Symptoms: Painful itching, mild pruritus, and burning.

• Commonly Affected Areas: Lower extremities, ear pinna, palms, soles, and oral mucosa.

Histologic Features -

Histological sections reveal distinct areas of compact lamellar hyperkeratosis with focal parakeratosis. The epidermis beneath these hyperkeratotic areas is atrophic compared to the adjacent skin, with a reduced or absent granular layer. Additionally, the papillary dermis shows a dense, band-like infiltrate of small lymphocytes mixed with histiocytes, and there is also vasodilation of superficial vessels.

What Is the Cause of Flegel Disease?

Flegel disease or hyperkeratosis lenticularis perstans (HLP), is a disease with an unknown etiology. Abnormal keratinization or an inflammatory process might be a pathogenic cause of Flegel disease or hyperkeratosis lenticularis perstans (HLP). After finding focal parakeratosis with neutrophils in the stratum corneum, Fernandez-Flores and Manjon suggest Flegel disease as an inflammatory process with periods of exacerbation and remission. Decreased numbers or a loss of odland bodies, which are important in the normal process of desquamation, are reported ultrastructurally. A decrease in the number of odland bodies leads to abnormal keratinization.

Flegel disease or hyperkeratosis lenticularis perstans (HLP), is a rare cutaneous condition with an unknown etiology. Sun exposure might cause Flegel disease. It is rarely seen in families with skin and gastrointestinal cancers. Pathophysiological studies of this disease revealed that aberrant lamellar granules in lesional skin are the contributing factor in releasing lipids that are essential for the process of desquamation. Without normal desquamation, hyperkeratosis occurs due to this pathophysiology.

Who Is at Risk of Flegel Disease?

Basically, Flegel disease, or hyperkeratosis lenticularis perstans (HLP), is a rare disease affecting people in their middle age between the third and fourth decade of life. Middle-aged Caucasians are at risk of developing Flegel disease. It is also found that people with diabetes and hyperthyroidism are at risk of developing hyperkeratosis lenticularis perstans (HLP). It is genetic-based, and it follows in certain families.

How to Confirm Flegel Disease?

A skin biopsy is done. Flegel disease is characterized by hyperkeratotic lesions. Histopathological features include focal parakeratosis, basket weave-like orthokeratosis on either side, a discrete area of lamellar and compact hyperkeratosis, a granular cell layer that is very thin or absent, loss of rete ridges, acanthosis, and spongiosis that are present, a basal layer with cytoid bodies, and edematous lymphocytic infiltration in the papillary dermis. The stratum corneum layer shows hyperkeratosis. Clinical findings should be correlated with the biopsy reports. The histopathological findings of Flegel disease, hyperkeratosis lenticularis perstans, or HLP reveal the features mentioned below.

• Hyperkeratosis.

• Parakeratosis.

• Absence of granular layer or thin granular layer.

• Loss of rete ridges.

• Acanthosis.

• Spongiosis.

• Basal layer with cytoid bodies.

• Edematous.

• Lymphocytic infiltration.

• Stratum corneum shows hyperkeratosis.

• Vasodilation of superficial blood vessels.

What Is the Differential Diagnosis of Flegel Disease?

The features of Flegel disease, hyperkeratosis lenticularis perstans, or HLP are also seen in other conditions. Correlation and comparison of features will help in the differential diagnosis.

Some of the disorders associated with Flegel disease are listed below.

• Keratosis pilaris.

• Darier disease.

• Lichenoid drug reaction.

• Lichen planus.

• Stuccokeratosis.

• Kyrle disease.

• Superficial actinic porokeratosis.

• Scurvy.

• Hyperkeratosis follicularis.

What Is the Treatment of Flegel Disease?

However, the lesions are asymptomatic, so treating the individual with the cosmetic urge is important. It is observed that primary lesions are highly resistant to treatment. Required topical steroids are the first line of therapy to reduce the atrophy effects. Fluorouracil, a 5 percent cream, is considered a good treatment approach. Another approach is the surgical method .short-term psoralen with ultraviolet radiation A is also considered for the treatment of F

1. Medical Treatment for Flegel Disease -

• Topical 5-fluorouracil cream is used.

• Topical and systemic retinoids.

• Oral vitamin A.

• Oral retinoids such as acitretin or isotretinoin.

• Calcipotriene-vitamin D .

• Topical corticosteroids.

• Keratolytics.

• Emollients.

2. Physical Modalities for Flegel Disease -

• PUVA therapy - Psoralen with ultraviolet A can be done to improve skin conditions.

3. Surgical Treatment for Flegel Disease -

• Ablative treatments include carbon dioxide lasers.

• Curettage.

• Dermabrasion.

• Electrocoagulation.

• Cryotherapy, where a cold instrument is used to destroy abnormal tissue.

• Photodynamic therapy.

It is proven with an 80 to 90 percent success rate with photodynamic therapy using 5-aminolevulinic acid or ALA, which is activated by the blue light of 417 nm. After subsequent treatments, a 63-year-old woman was noted with the best results showing improvements in skin texture and appearance. The only side effect is mild erythema in every treatment.

Conclusion

Flagel disease or hyperkeratosis lenticularis perstans (HLP) is a rare benign cutaneous condition. Patient awareness is important, and the treatment is all done to manage the cosmesis of the patient. However, Flegel disease of hyperkeratosis lenticularis perstans (HLP)is a disease that causes no mortality.