Neoplasms of the Skin

Seborrheic dermatitis is a common chronic, relapsing skin disorder that presents as erythematous plaques with greasy, yellow scales in susceptible areas (scalp, face, and trunk). Seborrheic dermatitis has a biphasic incidence, occurring in two peaks: first in infants, then in adolescence and early adulthood. Although the exact etiology is unknown, pathologic mechanisms have been observed involving the sebaceous glands and Malassezia on the skin. Topical medications are used for acute exacerbation or maintenance treatment. These options aim to inhibit skin colonization (antifungal agents), reduce inflammation (steroids, calcineurin inhibitors), and loosen scales and crusts (keratolytic agents). Severe and refractory seborrheic dermatitis may warrant the use of systemic antifungal medications.

Lentigo maligna is melanoma in situ, a precancerous lesion that may progress to an invasive melanoma (specifically lentigo maligna melanoma subtype). This condition typically occurs in sun-damaged areas (e.g., face and neck) of elderly patients. Lentigo maligna presents as a brown macule with color variegation and asymmetrical borders that grow slowly. The lesion should be biopsied to confirm a diagnosis and surgical excision with a safety margin is the 1st-line treatment.

Basal cell carcinoma is the most common skin malignancy. This cancer arises from the basal layer of the epidermis. The lesions most commonly appear on the face as pearly nodules, often with telangiectatic blood vessels and ulceration in elderly individuals. Diagnosis is established by tissue biopsy. Despite having low metastatic potential, basal cell carcinoma should be treated adequately because it is locally aggressive and destructive to tissues. Complete surgical excision is the main treatment method. Long-term prognosis is excellent with adequate management.

Seborrheic keratosis (SK) is the most common benign epithelial cutaneous neoplasm. The condition consists of immature keratinocytes. Seborrheic keratosis is the most common benign skin tumor in middle-aged and elderly adults and presents as a sharply demarcated, exophytic, skin lesion that may be tan or black and has a “stuck-on” appearance. Pruritus or pain can occur if these lesions become secondarily inflamed by trauma, especially if they are within the skin folds. Genetics are thought to play a role, but the pathogenesis is uncertain. The most common mutations involve two oncogenes: fibroblast growth factor receptor 3 (FGFR3) and PIK3CA. There is a familial predisposition to develop a high number of seborrheic keratoses. Treatment is not necessary, as this is a benign condition, but cryotherapy, curettage or electrodesiccation can be performed for discomfort or cosmetic concerns.

Human herpesvirus 8, also known as Kaposi sarcoma–associated herpesvirus, is a double-stranded DNA virus belonging to the Herpesviridae family. This uncommon oncogenic virus causes Kaposi sarcoma (an AIDS-defining condition), primary effusion lymphomas, and multicentric Castleman disease mainly in immunocompromised patients. The process occurs through the induction of cellular growth activity and the inhibition of apoptosis in infected cells.

Atopic dermatitis, also known as eczema, is a chronic, relapsing, pruritic, inflammatory skin disease that occurs more frequently in children, although adults can also be affected. The condition is often associated with elevated serum levels of IgE and a personal or family history of atopy. Skin dryness, erythema, oozing, crusting, and lichenification are present. Pruritus is a cardinal symptom. Diagnosis is established clinically. The mainstays of management are avoidance of triggers, emollients, and topical corticosteroids.

Cutaneous squamous cell carcinoma (cSCC) is caused by malignant proliferation of atypical keratinocytes. This condition is the 2nd most common skin malignancy and usually affects sun-exposed areas of fair-skinned patients. The cancer presents as a firm, erythematous, keratotic plaque or papule. Histopathologic examination should be done for all suspected cases, as many lesions, such as actinic keratosis, mimic the appearance of SCC. Surgical excision is the mainstay of treatment. Overall prognosis is excellent for completely excised lesions, but certain high-risk features may predispose to metastatic disease and poor outcomes.

Melanoma is a malignant tumor arising from melanocytes, the melanin-producing cells of the epidermis. These tumors are most common in fair-skinned individuals with a history of excessive sun exposure and sunburns. Melanomas usually present as pigmented skin lesions, but they can occur on mucosal surfaces, such as in the eyes, anal canal, and genital regions. Common findings may include Asymmetry of the lesion, irregular Border, varying Color, > 6 mm Diameter, and Evolving features (ABCDE). Definitive diagnosis is established with biopsy. Treatment relies primarily on surgical excision. The prognosis is very good for early-stage lesions but quite dismal for metastatic disease. Of all the skin malignancies, melanoma generally carries the worst prognosis.

Human immunodeficiency virus (HIV) infection is a sexually transmitted or blood-borne infection that destroys CD4 T cells. Chronic HIV infection and depletion of CD4 cells eventually results in acquired immunodeficiency syndrome (AIDS), which can be diagnosed by the presence of certain opportunistic diseases called AIDS-defining conditions. These conditions include a wide spectrum of bacterial, viral, fungal, and parasitic infections as well as several malignancies and generalized conditions. These serious and life-threatening diseases are generally not seen in immunocompetent patients. Treatment of HIV is very important in managing these diseases, and the incidence of AIDS-defining conditions has declined with the use of antiretroviral therapy.

Human immunodeficiency virus (HIV), a single-stranded RNA virus belonging to the Retroviridae family, is the etiologic agent of acquired immunodeficiency syndrome (AIDS). The human immunodeficiency virus is a sexually transmitted or blood-borne infection that attacks CD4+ T lymphocyte cells, macrophages, and dendritic cells, leading to eventual immunodeficiency. The presentation is marked by constitutional symptoms such as lymphadenopathy and fever. Further progression predisposes to opportunistic infections and malignancies. Diagnosis is by enzyme immunoassay for HIV-1 and -2. Additional tests include HIV viral load, genotyping, and CD4+ T lymphocyte count to determine therapy and evaluate treatment response and disease progression. Immediate treatment with combination antiretroviral therapy is recommended.

Nevi (singular nevus), also known as “moles,” are benign neoplasms of the skin. Nevus is a non-specific medical term because it encompasses both congenital and acquired lesions, hyper- and hypopigmented lesions, and raised or flat lesions. Additionally, nevi can be found within different depths of the layers of the skin and originate from various types of cells (e.g., melanocytic, connective tissue, vascular). Nevi also have a wide variety of characteristic forms, which must be well understood in order to differentiate nevi from malignant melanoma. In this concept page, we will cover the basic classifications and most common types of nevi as well as the clinical criteria used to assess them.

Tinea infections are a group of diseases caused by fungi infecting keratinized tissue (hair, nails, and skin). These infections are termed dermatomycoses and are caused by the dermatophyte fungi. There are approximately 40 dermatophyte fungi that are part of 3 genera, including Trichophyton, Epidermophyton, and Microsporum. These infections can affect any part of the body but occur most often in warm, moist regions like the groin and the feet. The diagnosis is clinical with characteristic skin findings, but it can be confirmed with microscopy of skin scrapings. The treatment depends on the site and magnitude of infection but typically begins with topical antifungals like the -azole drugs and terbinafine, and it may progress to oral versions of these medications if topical treatment fails.