Radiological Features of Rare Dermatological Conditions

Introduction

The skin is regarded as the largest organ in our body. It comprises the outer covering of our entire body and is broadly composed of three main layers: the epidermis (top layer), the dermis (middle layer), and the hypodermis (bottom or fatty layer). Each layer is further subdivided into multiple layers. Skin is said to play a major role in protecting our body by acting as a barrier against varied microorganisms, ultraviolet light radiation, and supposed mechanical damage (if encountered). Medical science has witnessed innumerable skin disorders ranging from common allergic reactions to complex genetic diseases that may or may not be permanent. Skin conditions like psoriasis, eczema, and acne are common among all age groups and have multiple treatment protocols developed to treat them. However, certain skin disorders are quite uncommon. One may barely possess any knowledge about these skin ailments owing to their extreme rarity in occurrence. These are termed rare skin diseases.

What Are Rare Skin Diseases?

Typically, all common skin conditions are quite mild and easy to treat with topical or parenterally administered medication. Some may even resolve without any specific treatment. Rare skin diseases, however, turn out to be quite severe in form and require specialized medical attention. Some rare skin conditions are observed to be inherited, meaning they are genetically predisposed in an individual. A list of rare skin disorders include:

1. Argyria: This disease is characterized by an abnormally high amount of silver accumulation in the layers of the skin. Possible reasons for this are occupational exposure to silver, ingestion of silver, prolonged usage of silver-containing medication such as eye drops, or dental workups that constitute the use of silver amalgam filling. The radiographic findings of argyria can confirm in vivo silver concentration with the use of x-ray fluorescence.

2. Erythropoietic Protoporphyria: This is an inherited disease that is marked by a deficiency of the enzyme protoporphyrin IX. As a result, the amount of protoporphyrin protein increases in the blood, making the individual more sensitive to sunlight exposure. The common skin findings include redness, burning, blisters on the skin, and crusting of the skin. The radiographic findings demonstrate deformed extremities accompanied by scleroderma-like calcifications.

3. Harlequin Ichthyosis: This is a rare skin disorder that is also predisposed genetically. The disease involves extreme thickening of the skin present all over the body. The parts most affected are the eyelids, mouth, ears, and nose. The mobility of the hands and legs is reduced to a great extent due to the formation of shiny keratotic plaques over the skin that are separated by cracks. The diagnosis of ichthyosis can be made prenatally. The ultrasonography shows marked facial dysmorphism, an improperly formed nasal passage, and auditory organs. Very minimal fetal movement and a relatively stiff stature of the fetus are observed.

4. Elastoderma: Elastoderma is a rare skin disease is identified by the extreme looseness of the skin, particularly in the regions around the neck, elbows, and knees. The cause of the condition is yet to be discovered. The electron microscopy findings demonstrated grape-like spherical formations and erratic deposition of elastic material at the edges of elastic tissue fibers.

5. Pemphigus: This is a serious autoimmune skin disease that may prove to be fatal upon receiving untimely treatment. Pemphigus is characterized by the formation of sores and blisters over the surface of the skin, typically affecting the mouth, the nose, or the genitals.

What Is the Role Of Radiology In Diagnosing Skin Diseases?

The first approach to confirming a diagnosis of a skin condition or lesion is a clinical assessment of the skin. A skin specialist or dermatologist is skilled in forming a diagnosis simply by looking at the skin. A full diagnostic workup of the skin will include examining the patient from head to toe, specifically the scalp, the nails, and the mucous membranes. The use of a dermatoscope (magnifying lens complemented by a flashlight) is common in cases that require close observation to form a diagnosis. However, some skin conditions are way more complicated for the doctor to make out just by viewing the skin. Therefore, various other methodologies are adopted that aid in the diagnostic process of the skin disease. Some of these methods are:

1. Biopsy: A skin biopsy involves resection of a small piece of the affected skin. The doctor makes sure to numb the area with a local anesthetic before making the cut.

2. Scraping: Suspected fungal skin infections are tested by the scraping method, wherein the doctor scrapes a layer of the skin lesion and views it under a microscope to confirm the diagnosis.

3. Culture: The bacteria, fungi, or viruses present in a skin lesion sample are separated and cultured in a medium that facilitates their growth. This way, the nature of the microorganism involved in the disease can be suspected, and a proper treatment plan can be initiated.

4. Tzank Test: A tzank test is performed for skin diseases specifically caused by viruses such as herpes simplex and herpes zoster.

5. Diascopy: This particular test involves the use of pressure mechanics to observe any change in the color of the affected skin region. Skin lesions belonging to certain diseases whiten in appearance upon applying pressure, whereas others show no change in color.

6. Skin Tests (Patch Test, Intradermal Tests):

• A patch test is recommended to disclose any suspected allergic reaction to a foreign substance before it is put into full application. The skin usually responds within 48 to 96 hours of the patch test. A red or itchy skin rash is a confirmation that the product is allergic to the user. No change in skin color, texture, or condition means the product is safe for application.

• Intradermal tests refer to injecting small amounts of foreign substance into the superficial layers of the skin. The skin area is supervised for the next 72 hours for an abnormal reaction.

7. Imaging Studies: A new non-invasive approach to form a sound diagnosis of skin disease is ultrasound imaging. The use of ultrasound as a diagnostic tool has gained recent popularity in the field of dermatology owing to the accurate and timely results it provides. The mechanism through which ultrasound works is quite interesting to follow. It uses acoustic (sound) waves that travel through the layers of skin. The echoes reflected in return produce a visual for the doctor to comprehend. Other relatively expensive radiographic modalities include the MRI (magnetic resonance imaging) and CT (computed tomography).

Conclusion

The introduction of diagnostic imaging in the field of dermatology has proven extremely beneficial to both patients and clinicians due to the non-invasive approach it complements. A clear visualization of various diseases that affect both the musculoskeletal and cutaneous tissues is obtained with ease using radiographic diagnostic modalities. Patient care is advanced multi-folds when a radiologist and the clinician can identify the disease characteristics by reviewing the radiographic findings accurately. The hassle of making the patient undergo long, invasive procedures for diagnostic purposes can be kept below par in such cases. High-frequency ultrasonography, digital photographic imaging, optical coherence tomography, confocal microscopy, and artificial intelligence are some more examples of new and developing technology.