Cambridge University Press 978-1-107-43080-8 - Essentials of Surgical Pediatric Pathology Edited by Marta C. Cohen and Irene Scheimberg Excerpt More information Chapter Skin 1 Isabel Colmenero, Antonio Torrelo, and Miguel Reyes-Múgica Skin diseases are very frequent in children. Most of spongiotic vesicles. When large enough, these vesicles them, including the most common disorders, such as can be grossly appreciated. These vesicles contain lym- atopic dermatitis, hemangiomas, nevi, acne, or bacte- phocytes and/or Langerhans cells in most cases, but rial and viral infections, are readily diagnosed through sometimes eosinophils or neutrophils can be the dom- an adequate anamnesis and clinical examination. inant element. spongiotic dermatitis is further subclas- However, some skin tumors and inflammatory disor- sified into acute, subacute, and chronic. As the lesions ders may require a biopsy. The patient’s age and rele- progress, the spongiosis decreases and parakeratosis vant clinical history, in addition to the site from which appears. In the late stage the spongiosis is mild to the skin biopsy was obtained, should be known by the absent, but there is pronounced irregular acanthosis, pathologist. hyperkeratosis, and parakeratosis. A sound basis of pediatric dermatological epidemi- The pattern of SD is caused by a variety of clinical ology is necessary, since the entities most frequently conditions. These include atopic dermatitis, allergic/ observed in children differ significantly from those contact dermatitis, nummular dermatitis, dyshidrotic seen in adults. dermatitis, seborrheic dermatitis, drug reactions, Id The specimens and biopsies most frequently sent reaction, dermatophytosis, miliaria, Gianotti–Crosti for histopathological analysis in children are melano- syndrome, and pityriasis rosea (1). The differential cytic nevi, inflammatory dermatoses such as Henoch– diagnosis of spongiotic dermatitis is shown in Table 1.1. Schönlein purpura, psoriasis, pityriasis lichenoides, Atopic dermatitis is the most prevalent cause of pityriasis rosea, lichen planus, pityriasis rubra pilaris, spongiotic dermatitis, and is generally diagnosed clin- erythema multiforme, atopic dermatitis, granuloma ically; however, some atypical cases can occasionally annulare, and pigmented purpuric dermatosis, as undergo biopsy. well as infections, vascular anomalies and benign tumors/hamartomas/cysts. Genodermatosis and malignancies are rarely seen. Atopic dermatitis (AD) In this chapter, we will be dealing with the histo- Atopic dermatitis is a chronic, eczematous condition pathology features of the most commonly biopsied of the skin, often related to atopic states (including skin diseases in children. asthma, hay fever, and other allergic diseases). Clinical presentation: Atopic dermatitis affects Inflammatory skin disorders 5–15% of children in the industrialized world. Its prevalence has increased steadily in recent years, to We will follow the pattern analysis approach and become the most prevalent skin disease in children. discuss an important example in each pattern. The main clinical features include a combination of eczema, prurigo, and lichenification. It usually runs a Spongiotic dermatitis chronic course with exacerbations. Most cases of AD Spongiotic dermatitis (SD) is defined by the presence begin in infancy with head and face eczema that can of intraepidermal intercellular edema. Pronounced spread to the extensor areas of the limbs and trunk. By spongiosis results in the formation of intraepithelial the age of two, the typical flexural involvement Essentials of Surgical Pediatric Pathology, ed. Marta C. Cohen and Irene Scheimberg. Published by Cambridge University Press. 1 © Cambridge University Press 2014. © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-43080-8 - Essentials of Surgical Pediatric Pathology Edited by Marta C. Cohen and Irene Scheimberg Excerpt More information Chapter 1: Skin Table 1.1 Spongiotic dermatitis Usual type spongiotic dermatitis (spongiosis distributed randomly through the epidermis with no specific localization) * Contact dermatitis * Pompholyx * Juvenile plantar dermatosis * Autoeczematization (“id” reaction) * Papular acrodermatitis of childhood (Gianotti–Crosti) * Spongiotic drug reactions Miliarial spongiosis (intraepidermal edema centered on the acrosyringium) * Miliaria rubra Follicular spongiosis (intercellular edema in the follicular infundibulum) * Infundibulofolliculitis Figure 1.1 Atopic dermatitis. Subacute lesion showing mild * Atopic dermatitis spongiosis, exocytosis of lymphocytes, and parakeratosis, in a * Apocrine miliaria perifollicular distribution. * Eosinophilic folliculitis Pityriasiform spongiosis (microvesicles within areas of spongiosis that contain lymphocytes, histiocytes, and Langerhans cells) Genetics: Atopic dermatitis is due to a genetic * Pityriasis rosea defect in the skin barrier. In about 40% of patients, a * Pityriasiform drug reaction semi-dominant genetic defect in the FLG gene, encod- * Erythema annulare centrifugum ing the epidermal protein filaggrin, is responsible. * Nummular dermatitis Deficient filaggrin function leads to weaker corneo- * Lichen striatus cytes and skin barrier derangement, thus leading to an Neutrophilic spongiosis * Pustular psoriasis increased passage of irritants and allergens throughout * Pemphigus foliaceus the epidermis, and to a higher adherence of bacteria * IgA pemphigus due to impaired natural immunity (3,4). * Infantile acropustulosis Classification: Atopic dermatitis is a heterogeneous * Acute generalized exanthematous pustulosis disease; different types of genetic defects are supposed * Palmoplantar pustulosis * Staphylococcal toxic shock syndrome to result in an epidermal barrier defect. Most types of * Dermatophytoses and candidiasis eczema in infants are regarded as “atopic,” although * Pustular contact dermatitis there may be clinical differences that might reflect * Periodic fever syndromes different genetic backgrounds. Eosinophilic spongiosis Histology: Atopic dermatitis cannot be reliably or * Pemphigus consistently distinguished from other forms of eczem- * Bullous pemphigoid * Allergic contact dermatitis atous dermatitis based on assessment of histopatho- * Atopic dermatitis logical features alone. Biopsies of atopic dermatitis are * Arthropod bites usually taken from subacute or chronic lesions, so * Eosinophilic folliculitis parakeratosis, epidermal hyperplasia, and superim- * Incontinentia pigmenti (first stage) * Drug reactions posed features of lichen simplex chronicus are typical, * Autoeczematization (“id” reaction) rather than prominent spongiosis (Figure 1.1). * Still’s disease Secondary impetiginization with Staphylococcus aur- * Wells’ syndrome eus or secondary herpes simplex virus infection (eczema herpeticum) may occur. affecting mainly the elbow and knee folds is patent. Chronic disease and a vicious circle of itch and scratch Psoriasiform dermatitis lead to a typical thickening of the skin named lichen- Psoriasiform dermatitis is characterized by the pres- ification. Prurigo lesions, consisting of papules and ence of regular epidermal hyperplasia, elongation of 2 papulo-vesicles scattered throughout the skin surface the rete ridges, hyperkeratosis, and parakeratosis. are also common in older children and adolescents (2). Thinning of the suprapapillary plates, a superficial © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-1-107-43080-8 - Essentials of Surgical Pediatric Pathology Edited by Marta C. Cohen and Irene Scheimberg Excerpt More information Chapter 1: Skin Table 1.2 Psoriasiform dermatitis Table 1.3 Interface dermatitis * Psoriasis Interface dermatitis, vacuolar-type * Psoriasiform drug eruption * Erythema multiforme * Pityriasis rubra pilaris * Erythema multiforme-like drug eruption * Lichen simplex chronicus * Fixed drug eruption * Chronic spongiotic dermatitides * Lichen sclerosis et atrophicus * Erythroderma * Erythema dyschromicum perstans * Pityriasis lichenoides chronica * Lupus erythematosus * Inflammatory linear verrucous epidermal nevus * Dermatomyositis * Chronic fungal infections * Viral exanthemas * Lamellar ichthyosis * Phototoxic dermatitis * Secondary syphilis * Acute radiation dermatitis * Pellagra and other nutritional deficiencies * Acute graft vs. host disease Interface dermatitis, lichenoid-type * Lichen planus * fl fi Lichenoid drug eruption perivascular in ammatory cell in ltrate, and dilated, * Lupus erythematosus tortuous blood vessels within these papillae are also * Chronic graft vs. host disease present. Numerous conditions can result in psoriasi- * Lichen nitidus form dermatitis (Table 1.2). * Pigmented purpuric dermatosis * Pityriasis lichenoides chronica * HIV dermatitis * Syphilis Psoriasis * Mycosis fungoides Psoriasis is a common, chronic, relapsing, papulo- * Urticaria pigmentosa squamous disorder of the skin with highly variable presentation. superficial perivascular predominantly lymphocytic Clinical presentation: Psoriasis is very common, dermal infiltrates. Neutrophilic spongiosis, intraepider- and around 20% of cases begin in childhood or mal spongiform pustules (of Kogoj), and neutrophil adolescence. The main clinical feature is the psoriatic aggregates in the stratum corneum (Munro microab- plaque. It appears as an erythematous, flat-topped scesses) can also be present. plaque, with thick, adherent scales, generally on the extensor surfaces of the elbows and knees, but areas