Definition:

Kaposi sarcoma (KS) is a vascular neoplasm first described in 1872 by Moritz Kaposi as “idiopathic multiple pigmented sarcoma of the skin.” Historically, it was seen primarily in elderly men of Mediterranean, Eastern European, or Ashkenazi descent. Although sporadically observed in organ transplant recipients and in African populations, KS gained major attention during the AIDS epidemic as a defining illness. All clinical forms of KS are associated with human herpesvirus 8 (HHV-8), also known as Kaposi sarcoma-associated herpesvirus (KSHV).

 

Epidemiology:

KS manifests in four clinical variants:

• Classic KS: Primarily affects elderly men of Mediterranean or Eastern European descent; typically slow-growing and indolent.
• African endemic KS: Common among children and adults in Sub-Saharan Africa; includes aggressive lymphadenopathic forms.
• Iatrogenic KS: Occurs in immunosuppressed individuals, especially post-organ transplantation or with chronic immunosuppressive therapies (e.g., corticosteroids, calcineurin inhibitors). Lesions may regress upon reduction of immunosuppression.
• AIDS-related (epidemic) KS: Predominantly affects individuals with HIV/AIDS. It was particularly prevalent in the 1980s but has declined with the advent of highly active antiretroviral therapy (HAART).

 

Etiology:

KS originates from endothelial cells of blood vessels and lymphatics, though the exact lineage remains mixed. HHV-8 infection plays a central role by altering endothelial cells, promoting lymphangiogenic and mesenchymal features through endothelial to mesenchymal transition. The virus encodes homologs of cellular genes that stimulate proliferation, inhibit apoptosis, and promote angiogenesis. Immunosuppression, cytokine release, and chronic inflammation further contribute to tumor development. Transmission of HHV-8 occurs primarily through saliva but can also involve sexual and possibly arthropod vectors. The virus may remain latent and reactivate under conditions of immune dysfunction.

 

Clinical Features:

• Classic KS: Presents as slowly enlarging, pink to red-violet macules on the lower extremities that may evolve into plaques or nodules. Lesions can be unilateral initially but often become multifocal over time.
• AIDS-related KS: Characterized by widespread, violaceous plaques and nodules affecting the skin, mucous membranes, gastrointestinal tract, and lymph nodes. Lesions can worsen during immune reconstitution inflammatory syndrome (IRIS).
• Iatrogenic KS: Typically resolves with reduction of immunosuppressive therapy.
• African endemic KS: Manifests in nodular, florid, infiltrative, or lymphadenopathic forms, with the lymphadenopathic type primarily affecting children. Lymphedema and visceral involvement (oral cavity, gastrointestinal tract, lungs) are common in advanced disease.

 

Diagnosis:

Diagnosis is clinical but confirmed by histopathology showing spindle-shaped endothelial cells, slit-like vascular spaces, and HHV-8 positivity by immunohistochemistry or PCR.

 

Management:

Management depends on the clinical variant and disease extent:

• HIV-associated KS: Initiation of HAART is critical and often leads to lesion regression.
• Localized disease: Options include cryotherapy, radiotherapy, or intralesional chemotherapy.
• Extensive disease: Systemic chemotherapy (liposomal doxorubicin, paclitaxel) is indicated.
• Iatrogenic KS: Reduction or modification of immunosuppressive therapy may lead to lesion regression.

 

Written by: 

Raneem Alahmadi, Medical Intern.

Revised by: 

Naif Alshehri, Medical Intern

Resources:

Bolognia 5th edition

Dermnet

Background

Hand, Foot, and Mouth Disease (HFMD) is a common, self-limiting viral infection primarily affecting children under five years old. Characterized by a distinctive rash and oral lesions, HFMD occurs worldwide, with increased incidence during late summer and early autumn. 

 

Etiology

HFMD is predominantly caused by coxsackievirus A16 and enterovirus 71, both members of the Enterovirus genus. Transmission occurs through direct contact with nasal secretions, saliva, blister fluid, or stool of infected individuals. The virus can also spread via respiratory droplets or contaminated surfaces, making it highly contagious, especially in childcare settings. 

 

Clinical Features

After an incubation period of 3 to 5 days, initial symptoms include fever, malaise, and sore throat. Within a few days, painful oral lesions develop, appearing as red macules that progress to vesicles and ulcers, commonly located on the tongue, gums, and inside of the cheeks. Simultaneously or shortly after, a non-itchy rash emerges on the palms, soles, and sometimes the buttocks, presenting as red macules or vesicles. These skin lesions are typically not painful. 

 

Diagnosis

Diagnosis is primarily clinical, based on the characteristic presentation of oral ulcers and a distinctive rash on the hands and feet. Laboratory tests are generally not required but may be used in atypical cases or when complications arise. The preferred confirmatory test is polymerase chain reaction (PCR), which can detect enteroviruses from throat swabs, stool samples, or vesicle fluid. Serologic tests and viral culture are rarely performed due to limited clinical utility and slow turnaround times.

 

Management

Treatment focuses on symptomatic relief, as HFMD is self-limiting and typically resolves within 7 to 10 days. Recommended measures include:

• Pain Relief: Administering acetaminophen or ibuprofen to alleviate fever and discomfort.
• Hydration: Encouraging fluid intake to prevent dehydration, especially in children with painful oral lesions.
• Topical Treatments: Using mouthwashes or sprays to reduce oral discomfort.

Antiviral medications are not indicated, and antibiotics are ineffective unless a secondary bacterial infection develops. 

 

Prevention

Preventative strategies focus on limiting the spread of the virus:

• Hygiene Practices: Regular handwashing with soap and water, especially after diaper changes or using the toilet.
• Cleaning: Disinfecting contaminated surfaces and objects, such as toys and doorknobs.
• Isolation: Keeping infected individuals, particularly children, away from school or daycare during the acute phase of the illness to reduce transmission.

Currently, no vaccines are available for HFMD, making these preventive measures crucial. 

 

Prognosis

HFMD generally has an excellent prognosis, with most individuals recovering fully without complications. However, rare severe manifestations can occur, especially with enterovirus 71 infections, including neurological complications like aseptic meningitis or encephalitis. Prompt medical attention is essential if neurological symptoms or signs of dehydration arise.

In conclusion, Hand, Foot, and Mouth Disease is a common viral illness with distinctive clinical features. Understanding its etiology, clinical presentation, and management strategies is vital for effective care and prevention. 

 

Written by: 

Dr Renad AlKanaan

Revised by: 

Naif Alshehri, Medical Intern

References:

Dermnet

UpToDate

Bolognia 5th Edition

Definition:

Congenital Dermal Melanocytosis, commonly known as Mongolian spots, is a congenital dermal pigmentation that appears as blue-grey patches on the skin, typically affecting the lower back and buttocks of newborns. It is a benign form of birthmark caused by the presence of melanocytes in the dermis.

 

Epidemiology:

Dermal melanocytosis is usually present at birth or develops within the first few weeks of life. In most cases, the lesions regress during early childhood, though persistence into adulthood has been documented, with a prevalence of 4% in Japanese males aged 18–22 years.

The incidence of dermal melanocytosis varies significantly based on ethnicity, occurring in nearly 100% of Malaysian, Mongolian, Japanese, Chinese, and Korean newborns; 87% of Bolivian Indigenous populations; 65% of Black individuals in Brazil; 17% of White individuals in Bolivia; and only 1.5% of White persons in Brazil. These variations suggest a genetic influence on the persistence of dermal melanocytes. Histologically, traces of dermal melanocytosis have been found in the presacral area of all newborns, regardless of race.

 

Etiology:

The characteristic blue-grey color of dermal melanocytosis results from the presence of melanin-producing melanocytes in the middle to lower dermis. During fetal development, melanocytes appear in the dermis around the 10th week of gestation and typically migrate to the epidermis or undergo apoptosis. However, in certain areas—such as the sacral region, scalp, and distal extremities—some melanocytes remain in the dermis, leading to persistent pigmentation.

The bluish appearance is due to the Tyndall effect, in which shorter wavelengths (blue and violet) are more likely to be scattered and reflected than longer wavelengths (red, orange, and yellow), giving the lesions their characteristic coloration.

 

Clinical Features:

Lumbosacral dermal melanocytosis typically presents as bluish-grey macular patches on the sacrococcygeal, lumbar, and gluteal regions. The patches can be round, oval, or irregular in shape, ranging in size from a few centimeters to over 20 cm. While they are usually limited to less than 5% of the body surface area, extrasacral variants can involve other areas such as the back, limbs, or face.

The affected skin remains unchanged apart from the pigmentation—there is no thickening, textural alteration, or other skin abnormalities. Persistent or extensive dermal melanocytosis may be associated with phakomatosis cesioflammea or phakomatosis cesiomarmorata, warranting further evaluation in such cases.

 

Diagnosis:

The diagnosis of dermal melanocytosis is clinical, based on the characteristic appearance and location of the lesions. No further testing is typically required unless an associated condition is suspected.

 

Management:

Dermal melanocytosis is a benign condition that usually fades spontaneously by the age of four. No treatment is necessary in most cases. However, in instances where lesions persist into adulthood, cosmetic camouflage or laser therapy (such as those used for nevus of Ota) may be considered for aesthetic reasons.

 

Written by: 

Raneem Alahmadi, Medical Intern

Revised by: 

 Naif Alshehri, Medical Intern

Resources:

Bolognia 5th edition

Dermnet

 

Definition

Reactive perforating dermatoses are characterized by the transepidermal elimination of dermal connective tissue through the epidermis. 

Reactive perforating collagenosis (RPC) is a form of perforating dermatosis involving the extrusion of altered collagen fibers. RPC can be inherited or acquired, with inherited cases often triggered by trauma or cold exposure. 

The acquired form is more common and frequently associated with systemic conditions such as diabetes mellitus or chronic kidney disease, particularly in patients undergoing dialysis, where pruritus-induced trauma exacerbates the condition.

 

Epidemiology : 

RPC occurs globally without a clear racial predilection. The inherited form is rare and often familial, with onset typically in infancy or early childhood. It may follow either an autosomal dominant or autosomal recessive inheritance pattern. In contrast, the acquired form is more prevalent and usually develops later in life, showing a higher incidence in women with a female-to-male ratio of approximately 3:1. Acquired RPC is strongly associated with chronic systemic illnesses such as diabetes and chronic kidney disease,

 

Etiology

The exact pathogenesis of RPC remains uncertain, but key factors include:

1. Inherited Form:

 – Linked to genetic abnormalities in collagen structure, leading to focal damage and extrusion through the epidermis.

 – Triggers such as trauma or cold weather often exacerbate the condition.

2. Acquired Form:

 – Associated with microvascular insufficiency and elevated plasma fibronectin levels, commonly seen in diabetes and chronic kidney disease.

 – Abnormal glycosylation of collagen types I and III in diabetes may alter collagen fibers, contributing to their extrusion.

 – Superficial trauma, scratching, and cold exposure lead to epidermal thinning and necrobiosis in susceptible patients.

 

Clinical Features

RPC typically manifests as a papulonodular mucocutaneous disorder. Lesions appear as red-brown umbilicated papules or nodules with a central keratotic plug and an erythematous halo. The size of the lesions can range from a few millimeters to 10 mm, though rare giant forms measuring up to 10 cm have been reported.

 Lesions are intensely pruritic but are rarely painful or tender. Inherited RPC often affects the hands, elbows, and knees, while the acquired form commonly involves the legs. In both forms, the distribution is generally symmetrical, and lesions may appear more widely scattered or even generalized. A hallmark feature of RPC is the Koebner phenomenon, where new lesions develop in response to trauma or scratching. Lesions typically resolve spontaneously within 6 to 10 weeks, though they may leave post-inflammatory hyperpigmentation or scarring.

 

Diagnosis 

Diagnosis is primarily clinical, based on characteristic lesions and associated systemic conditions.

 – Dermoscopy: May reveal central keratotic plugs and erythematous halos.

 – Skin Biopsy: Multiple biopsies are often required to confirm the histopathological findings, including transepidermal elimination of altered collagen.

 

Management

The management of RPC can be challenging, particularly in the acquired form, as it often involves addressing both the skin lesions and any underlying systemic conditions. Treatment typically focuses on reducing pruritus, minimizing trauma, and promoting lesion healing.

– Topical Treatments:

• Corticosteroids: Superpotent formulations under occlusion can reduce inflammation.
• Retinoids: Topical agents like tretinoin may aid in reducing keratotic plugging.
• Emollients: Improve skin hydration and barrier function.

– Systemic Therapies:

• Antihistamines: Sedating antihistamines help alleviate itching and improve sleep.
• Oral Retinoids: Acitretin can reduce lesion severity.
• Allopurinol: May be considered for refractory cases.

– Procedural Interventions:

• Intralesional Corticosteroids
• Cryotherapy or Curettage

– Phototherapy:

• Broadband or Narrowband UVB: Particularly beneficial for patients with chronic kidney disease, as it can relieve pruritus and improve skin lesions.

– Lifestyle Modifications:

• Avoid scratching and trauma to the skin to prevent exacerbations. Optimize management of systemic diseases like diabetes and renal dysfunction.

 

 

Written by: 

Raneem Alahmadi, Medical Intern.

Revised by: 

Naif Alshehri, Medical Intern.

Resources:

Bolognia 5th edition

Dermnet

Introduction

Dupilumab (Dupixent®) is a monoclonal antibody therapy designed to treat inflammatory conditions, primarily atopic dermatitis. It is the first biologic treatment approved for moderate to severe atopic dermatitis and has since been expanded to other allergic and inflammatory diseases. By blocking specific immune signaling pathways, dupilumab offers an effective alternative for patients who do not respond adequately to conventional therapies.

 

Mechanism of Action

Dupilumab is a human IgG4 monoclonal antibody that specifically binds to the IL-4Rα subunit, a key component of the receptor shared by interleukin-4 (IL-4) and interleukin-13 (IL-13). These two cytokines play a crucial role in Th2-mediated inflammation, which is a major driver of conditions like atopic dermatitis and asthma. By inhibiting IL-4 and IL-13 signaling, dupilumab reduces inflammation, improves skin barrier function, and alleviates symptoms.

 

Indications

Dupilumab is FDA-approved for the treatment of:

• Atopic dermatitis (eczema) in patients ≥6 months old with moderate-to-severe disease that is inadequately controlled with topical treatments.
• Prurigo nodularis in adults.
• Asthma in patients ≥6 years old with moderate-to-severe disease.
• Eosinophilic esophagitis in patients ≥12 years old.
• Chronic rhinosinusitis with nasal polyps in adults.

Additionally, off-label uses of dupilumab are being explored for spontaneous chronic urticaria, nummular eczema, allergic contact dermatitis, chronic hand eczema, bullous pemphigoid, and Netherton syndrome.

 

Dosage and Administration

Dupilumab is administered via subcutaneous injection, with dosing dependent on age and weight:

• Adults and children (≥60 kg): 600 mg loading dose, then 300 mg every 2 weeks.
• Children (30–59 kg): 400 mg loading dose, then 200 mg every 2 weeks.
• Children (15–29 kg, ≥6 years old): 600 mg loading dose, then 300 mg every 4 weeks.
• Children (5–14 kg, ≤5 years old): 200 mg every 4 weeks.

 

Contraindications and Precautions

Dupilumab is contraindicated in patients with a known hypersensitivity to the drug or its components. Additionally, live vaccines should be avoided, and patients should be up to date on their vaccinations before starting therapy.

Patients with serious active helminth infections (parasitic worms) should be treated before starting dupilumab.

 

Adverse Effects

While generally well-tolerated, dupilumab can cause certain side effects, the most common being:

• Injection site reactions
• Ocular diseases (conjunctivitis, dry eyes, blepharitis, keratitis)
• Herpes infections
• Atopic dermatitis exacerbation
• Nasopharyngitis (common cold symptoms)
• Headache and upper respiratory infections

Ocular side effects occur in approximately 10% of patients and usually develop within the first few weeks to months of treatment. Artificial tears, antihistamine eye drops (e.g., ketotifen), corticosteroids, cyclosporine, and tacrolimus ointment may be used for management.

Some patients may also experience facial or neck erythema, or dermatitis that is possibly linked to rosacea, allergic contact dermatitis, or Malassezia related dermatitis. 

Rare but reported conditions associated with dupilumab include psoriasiform eruptions, lichen planus-like reactions, and eosinophilic granulomatosis with polyangiitis.

 

Clinical Outcomes and Efficacy

Clinical trials have demonstrated that 40–50% of adolescents and adults receiving dupilumab alone, and 60–70% of children or adults receiving it in combination with topical corticosteroids, achieve a 75% improvement in their Eczema Area and Severity Index (EASI-75).

 

Conclusion

Dupilumab has revolutionized the management of atopic dermatitis and other Th2-driven inflammatory conditions, offering a safe and effective option for patients with moderate-to-severe disease. While its side effects, particularly ocular symptoms, should be monitored, its benefits in reducing inflammation and improving quality of life make it a cornerstone therapy in dermatology and beyond.

 

Written by: 

Naif Alshehri, Medical Intern 

Resources: 

Saudi MOH Atopic Dermatitis Guidelines

Dermnet

Bolognia Dermatology Textbook 5th Edition

Muñoz-Bellido FJ, Moreno E, Dávila I. Dupilumab: A Review of Present Indications and Off-Label Uses. J Investig Allergol Clin Immunol. 2022;32(2):97-115. doi:10.18176/jiaci.0682

Second Picture Resource:

Bolognia Dermatology Textbook 5th Edition

 

Introduction

Pyogenic granuloma, also known as lobular capillary hemangioma, granuloma gravidarum, or pregnancy tumor, is a benign vascular lesion characterized by the rapid proliferation of capillary blood vessels in the skin or mucosa. Despite its name, it is neither pyogenic nor granulomatous. Modern research shows it arises due to reactive neovascularization without any infectious involvement.

 

Epidemiology

Pyogenic granulomas (PGs) can develop at any age but are most common in children, teenagers, and young adults. A slight male predominance is observed overall, except for oral lesions, which are more frequent in females due to hormonal influences like pregnancy or oral contraceptive use. Rare presentations include neonates with multifocal PGs or adults with eruptive disseminated forms.

 

Etiology and Pathogenesis

PGs are often linked to pre-existing trauma or irritation, hormonal changes, or specific medications. Minor trauma accounts for 7% of cases, while oral lesions are commonly associated with chronic irritation and poor dental hygiene. Hormonal changes during pregnancy or contraceptive use are significant factors, with 5% of pregnant women developing gingival PGs.
Medications like retinoids, protease inhibitors, and cancer-targeted therapies can also trigger PGs. Additionally, molecular studies have identified mutations in the BRAF and NRAS genes, which activate the MAPK signaling pathway, suggesting a neoplastic component in some cases.

 

Clinical Features

PGs typically present as painless, red nodules or polyps that grow rapidly over weeks. The lesions are highly friable, frequently ulcerating or bleeding after minor trauma. They stabilize at sizes usually under 1 cm but may persist indefinitely if untreated. Common sites include the gingiva, lips, fingers, face, and tongue.

Oral mucosal PGs often develop as pedunculated or sessile nodules on the gums or lips. These lesions may ulcerate, develop a yellow fibrinous surface, and cause minor discomfort. Rarely, satellite lesions may arise near a primary PG after trauma or irritation.

 

Dermoscopy and Histology

Dermoscopy
Dermoscopy reveals a distinct keratinized border forming a white collarette around the lesion. Vascular structures are prominent, with red homogeneous areas and white linear “rail lines” being hallmark features.

Histological Findings
Histologically, PGs are characterized by a lobular arrangement of capillaries in the dermis surrounded by inflammatory cells and fibromyxoid stroma. The epidermis is often thinned or ulcerated, and a peripheral collarette formed by elongated rete ridges is typically present. Signs of hemorrhage and inflammatory infiltrates, including lymphocytes and plasma cells, are common. Oral PGs may show an additional granulation tissue-like vascular proliferation pattern.

 

Differential Diagnosis

The differential diagnosis for PG depends on its location and presentation:

Cutaneous Differential Diagnosis

• Amelanotic melanoma: Most critical to exclude due to overlapping features.
• Bacillary angiomatosis: Especially in immunosuppressed patients.
• Kaposi sarcoma: Seen in HIV-positive individuals.
• Cherry angioma: Benign capillary proliferation.
• Irritated melanocytic nevus or wart: May mimic PG due to irritation.

Oral Differential Diagnosis

• Peripheral giant cell granuloma
• Peripheral ossifying fibroma

Histological Differential Diagnosis

• Cherry angioma
• Bacillary angiomatosis

 

Treatment

Treatment focuses on lesion removal and addressing contributing factors to prevent recurrence. Options include:

• • General Measures: Improving oral hygiene, removing trauma sources, and discontinuing triggering medications.
  • Topical Treatments: Timolol gel, imiquimod cream, cryotherapy, or table salt therapy (applied under occlusion).

• Procedural Treatments:

• • Shave excision with electrosurgery: The most common approach.
  • Curettage and cautery: Effective but with recurrence risk.
  • Pulsed dye laser: Safe and effective for smaller lesions, particularly in children.
  • Sclerotherapy: Using monoethanolamine oleate for minimal scarring.
  • Surgical excision: Offers lower recurrence rates, especially in gingival lesions.

 

Prognosis

Pyogenic granulomas are benign and rarely resolve spontaneously, except in postpartum cases. Recurrence is common, particularly in gingival lesions or cases with persistent irritation or inadequate treatment. With appropriate intervention, the prognosis is excellent.

 

Written by: 

Naif Alshehri, Medical Intern. 

Resources: 

Dermnet

Bolognia Textbook 5th Edition