INTRODUCTION — Disorders of the scalp can result from a wide variety of inflammatory, infectious, parasitic, neoplastic, and idiopathic dermatologic or systemic disorders. Often, the patient history and physical examination significantly narrow the differential diagnosis.
This topic discusses the clinical assessment of patients with scalp disorders and reviews multiple conditions that present with visible changes on the scalp. To aid with diagnosis, the disorders are organized according to important clinical features. The evaluation of hair loss, a clinical finding that occurs in some scalp disorders, is reviewed separately. (See "Evaluation and diagnosis of hair loss".)
PATIENT ASSESSMENT — The patient history and physical examination are often sufficient for identifying the most likely cause of a scalp eruption. In the remainder of cases, this information helps to narrow the differential diagnosis.
Relevant information from the patient history may include:
●Age of onset (eg, birth, infancy, childhood, or adulthood)
●Associated symptoms (eg, pruritus, pain, or systemic symptoms)
●Perceived inciting or exacerbating factors
●Personal history of skin disorders
●Hair and scalp care practices
●Occurrence of a similar condition in family members or cohabitants
The physical examination should include a thorough examination of the scalp. The clinician should note the presence of characteristic physical features such as scale, erythema, papules, nodules, pustules, blisters, erosions, and alopecia, as such features help to elucidate the most likely etiology. Because some disorders affecting the scalp also affect other areas of the skin, performance of a full skin examination is valuable.
Often, examination of the scalp is challenging because of hair covering the scalp area. Use of an additional light source is helpful and hair should be physically parted to allow for examination as much of the scalp area as possible.
In cases in which uncertainty about the diagnosis remains after the clinical evaluation, a scalp biopsy may aid with diagnosis. Depending on the suspected disorder and the size and shape of the involved area, a shave, punch, or excisional biopsy may be indicated. In particular, biopsies of some hair loss disorders can be difficult to interpret. Examination of the specimen by a dermatopathologist is often helpful in these cases. (See "Skin biopsy techniques" and "Evaluation and diagnosis of hair loss", section on 'Scalp biopsies'.)
The text below organizes disorders that commonly affect the scalp according to key clinical findings. Of note, some disorders may exhibit features from more than one of the listed categories.
SCALY PATCHES AND PLAQUES — Scaly patches or plaques on the scalp are typically an indicator of scalp inflammation. Concomitant erythema is often present. In children, tinea capitis, seborrheic dermatitis, and atopic dermatitis are common causes of scaly patches or plaques on the scalp. Seborrheic dermatitis, psoriasis, and allergic contact dermatitis are common causes in adults. Focal areas of erythema with overlying hyperkeratosis may represent actinic keratoses, particularly when found in middle-aged and older adults.
Of note, inflammatory conditions of the scalp may result in hair loss. In most cases, the associated hair loss is reversible. Permanent hair loss (cicatricial alopecia) can occur in inflammatory conditions that lead to irreversible damage to hair follicles, such as discoid lupus erythematosus and lichen planopilaris, forms of primary cicatricial alopecia (see 'Cicatricial alopecia' below). Untreated tinea capitis may also eventually cause permanent alopecia .
Most of the conditions described below can be diagnosed based upon recognition of classic clinical findings, with skin biopsy reserved for unclear or atypical presentations. The need for additional testing is indicated for disorders in which this is often helpful or necessary.
Tinea capitis — Tinea capitis is a dermatophyte infection that is a common cause of scaling scalp eruptions in children and an infrequent cause of scalp eruptions in adults. Trichophyton and Microsporum species are the most frequent causative organisms .
Tinea capitis presents as scaly patches or plaques with or without inflammation (picture 1A-B). Circular areas of scale and alopecia are common and hair breakage at follicular orifices can lead to the appearance of numerous dark-colored dots within the affected area. Posterior cervical adenopathy is common [2,3]. A potassium hydroxide (KOH) preparation or fungal culture from scale or a hair shaft in an involved area is useful for confirming the diagnosis (picture 2). (See "Office-based dermatologic diagnostic procedures", section on 'Potassium hydroxide preparation'.)
Seborrheic dermatitis — Seborrheic dermatitis is common in infants and adults. In infants, seborrheic dermatitis most frequently presents as an accumulation of yellowish, greasy scales on the scalp, a presentation often referred to as "cradle cap" (picture 4). Infants may also develop facial involvement or retroauricular involvement manifesting as erythematous patches or plaques with fine, greasy scale. Truncal, diaper-area, and intertriginous involvement are additional presentations (picture 5A-B). (See "Cradle cap and seborrheic dermatitis in infants".)
Of note, infants with Langerhans cell histiocytosis may present with seborrheic dermatitis-like eruptions with predilection for the scalp, trunk, or diaper areas (picture 6A-C). In Langerhans cell histiocytosis petechiae are often present. (See 'Langerhans cell histiocytosis' below.)
Seborrheic dermatitis in adolescents and adults is typically found on the face (particularly eyebrows and nasolabial folds), scalp, upper trunk, and postauricular areas (picture 7A-D) . Patients develop erythematous patches or plaques with overlying fine, greasy scale. In mild cases (ie, dandruff), erythema may be minimal or absent. Pruritus may be present. (See "Seborrheic dermatitis in adolescents and adults".)
Atopic dermatitis — Atopic dermatitis in infants often involves the face and scalp, presenting with erythematous, scaly patches and crusts (picture 8). Extensor surfaces are an additional common site of involvement (picture 9). The diaper-area is usually spared.
Scalp involvement is less common in older children and adults; a flexural distribution, particularly in the antecubital and popliteal fossae, is common in this population (picture 10). Erythematous patches, excoriated papules, lichenified plaques, and marked pruritus are common features. However, scalp involvement may occur, particularly in severe cases. (See "Atopic dermatitis (eczema): Pathogenesis, clinical manifestations, and diagnosis".)
Psoriasis — Psoriasis of the scalp tends to appear as erythematous plaques with overlying silvery scale (picture 11). Pruritus may be nonexistent to severe. Other manifestations of psoriasis may be present elsewhere, such as on extensor surfaces, elbows, knees, sacrum, or nails (eg, pitting, onycholysis, oil spots) (picture 12A-E). A family history of psoriasis is often present. (See "Psoriasis: Epidemiology, clinical manifestations, and diagnosis".)
Allergic contact dermatitis — Allergic contact dermatitis usually presents with erythematous, scaly patches or plaques on the scalp (picture 13). Severe cases may exhibit blistering, serous drainage, erosions, and crusting. Pruritus is usually significant. Use of hair care products is a common culprit. Patch testing is used to evaluate for the inciting antigen. (See "Clinical features and diagnosis of allergic contact dermatitis", section on 'Clinical features' and "Common allergens in allergic contact dermatitis", section on 'Hair care products'.)
Actinic keratosis — Actinic keratoses may appear on the scalp as single or multiple erythematous macules or small patches with overlying scale (picture 14). Adults with scalp hair loss, light skin color, and a history of significant sun exposure are most susceptible. The diameter of actinic keratoses usually ranges from a few millimeters to 2 cm. (See "Epidemiology, natural history, and diagnosis of actinic keratosis", section on 'Clinical features'.)
A small proportion of actinic keratoses progress to cutaneous squamous cell carcinoma. Size greater than 1 cm, induration, ulceration, tenderness, and rapid growth are among the signs that suggest a biopsy may be indicated to rule out squamous cell carcinoma. (See "Epidemiology, natural history, and diagnosis of actinic keratosis", section on 'Biopsy'.)
Less common disorders
Pityriasis amiantacea — Pityriasis amiantacea is an uncommon scalp condition characterized by the accumulation of thick scale that adheres tightly to the scalp and hair (picture 15). Involvement may be localized or widespread. The etiology is uncertain; it has been proposed that the disorder may be a reaction pattern observed in various scalp diseases (eg, psoriasis, seborrheic dermatitis, tinea capitis, or atopic dermatitis) . Secondary bacterial infection may occur.
The diagnosis of pityriasis amiantacea is made based upon the classic clinical appearance. A full skin examination aids in identifying an associated skin disorder. A KOH preparation or fungal culture is indicated if the clinical findings suggest tinea capitis.
Pemphigus foliaceus — Pemphigus foliaceus is an autoimmune blistering disorder in which superficial blistering results in erythematous patches or plaques with erosions, crusts, and scale (picture 16A-B). The scalp, face, and trunk are common sites of involvement. Pain or burning sensations may be present. The diagnosis of pemphigus foliaceus is confirmed based upon clinical, histologic, and immunopathologic findings . (See "Pathogenesis, clinical manifestations, and diagnosis of pemphigus", section on 'Pemphigus foliaceus' and "Pathogenesis, clinical manifestations, and diagnosis of pemphigus", section on 'Diagnosis'.)
Dermatomyositis — Dermatomyositis of the scalp usually presents as a pruritic eruption characterized by diffuse erythema with scale and atrophy (picture 17) [7,8]. Other cutaneous findings of dermatomyositis, such as a poikilodermatous eruption on the chest and extremities, Gottron papules on the dorsal hands, or a violaceous heliotrope eruption on the face are often present (picture 18A-E) . Muscle involvement is also usually present. (See "Clinical manifestations of dermatomyositis and polymyositis in adults".)
The diagnosis of dermatomyositis is usually based upon recognition of the characteristic skin findings, muscle weakness, and laboratory evidence of myositis. Skin biopsy may be helpful for ruling out other skin disorders, particularly when muscle involvement is absent. (See "Cutaneous dermatomyositis in adults: Overview and initial management", section on 'Patient evaluation'.)
Langerhans cell histiocytosis — Langerhans cell histiocytosis (LCH) is a rare disorder of histiocytes that can affect multiple organs. Both children and adults can develop LCH.
Skin involvement in LCH is most likely to manifest on the scalp, groin, trunk, and face (picture 6A-C). Patients may develop scaly or crusted erythematous to brown papules and thin plaques or other skin manifestations. Petechiae are often present within involved areas. Hypopigmentation may occur in patients with dark skin. A skin biopsy demonstrating Langerhans cells with kidney-shaped nuclei and positive staining for CD1a and langerin confirms the diagnosis . (See "Clinical manifestations, pathologic features, and diagnosis of Langerhans cell histiocytosis".)
PLAQUES WITHOUT SCALE — Nevus sebaceous, syringocystadenoma papilliferum, alopecia mucinosa, and cutaneous B-cell lymphoma are examples of skin conditions that can manifest as non-scaly plaques on the scalp. Nevus sebaceous can often be diagnosed based upon clinical examination due to its characteristic yellow-orange color. Skin biopsy is necessary to confirm a diagnosis of the other disorders.
Nevus sebaceous — Nevus sebaceous is a benign cutaneous hamartoma that typically first presents at birth or in early childhood and commonly occurs on the scalp. Affected patients exhibit a solitary, yellow-orange or tan, oval or linear hairless plaque (picture 19). In patients with dark skin, nevus sebaceous may be a dark brown color (picture 20). (See "Nevus sebaceus and nevus sebaceus syndromes".)
Nevus sebaceous typically becomes more prominent with age. As children enter early puberty, nevus sebaceous tends to become thicker, verrucous, or nodular (picture 21).
Nevus sebaceous may also occur as a feature of nevus sebaceous syndrome (also known as Schimmelpenning syndrome). In nevus sebaceous syndrome, nevus sebaceous is often extensive and patients have associated cerebral, ocular, or skeletal defects . (See "Nevus sebaceus and nevus sebaceus syndromes".)
Syringocystadenoma papilliferum — Syringocystadenoma papilliferum is an uncommon benign adnexal neoplasm with apocrine differentiation that has a predilection for the scalp. Syringocystadenoma papilliferum usually first appears at birth or in childhood and manifests as a single papule, multiple papules, or plaque (picture 22). Syringocystadenoma papilliferum may arise independently or within a preexisting nevus sebaceous .
The color of syringocystadenoma papilliferum is typically pink or red. At puberty the neoplasm grows in size and may take on a verrucous appearance. (See "Cutaneous adnexal tumors", section on 'Syringocystadenoma papilliferum'.)
Alopecia mucinosa — Alopecia mucinosa (also known as follicular mucinosis) is usually characterized by an erythematous or skin-colored indurated plaque with alopecia on the face or scalp (picture 23A-B). Follicular papules may be present. Alopecia mucinosa may be idiopathic or associated with mycosis fungoides .
Cutaneous B-cell lymphoma — Cutaneous B-cell lymphoma can present as solitary or multiple erythematous, red-brown, or violaceous papules, plaques, or nodules (picture 24). The head is a common site for the primary cutaneous follicle center lymphoma subtype of cutaneous B-cell lymphoma. A skin biopsy is necessary for diagnosis. (See "Primary cutaneous follicle center lymphoma".)
PAPULES AND NODULES — Nodular growths on the scalp may be a manifestation of cysts, benign cellular proliferation, or malignancy. Of the diagnoses reviewed below, pilar cyst, acne keloidalis nuchae, and juvenile xanthogranuloma can often be diagnosed clinically. A skin biopsy is recommended for the diagnosis of the other disorders.
Pilar cyst — Pilar cysts (also known as trichilemmal cysts) present as smooth, mobile, skin-colored nodules on the scalp (picture 25A-B). A punctum is usually absent. Spontaneous rupture may result in prominent inflammation. (See "Overview of benign lesions of the skin", section on 'Pilar (trichilemmal) cysts'.)
Acne keloidalis nuchae — Acne keloidalis nuchae is a common form of cicatricial (scarring) alopecia that primarily affects the occipital scalp. Males of African origin with Afro-textured hair are the population most commonly affected. Patients present with inflamed papules, pustules, and smooth dome-shaped keloid-like papules on the posterior scalp (picture 26). The condition may lead to the formation of large keloid-like plaques or nodules (picture 27A-B). (See "Acne keloidalis nuchae: Pathogenesis, clinical manifestations, and diagnosis".)
Dermoid cyst — Dermoid cysts are slow-growing, benign, subcutaneous nodules that develop along embryonic fusion planes and result from an abnormality during fetal development. The cysts are lined by stratified squamous epithelium and contain other cutaneous structures (eg, hair follicles, sweat glands, and sebaceous glands) . Dermoid cysts most frequently are found periorbitally, but may also appear on the scalp and other areas . Patients usually present in infancy or childhood with a firm nodule (typically 0.5 to 5 cm) that is fixed to the underlying bone or freely mobile (picture 28) . Midline dermoid cysts may have intracranial extension. (See "Skin nodules in newborns and infants", section on 'Dermoid cysts and sinuses'.)
Juvenile xanthogranuloma — Juvenile xanthogranuloma is a non-Langerhans cell histiocytosis that becomes evident at birth or in early childhood . Patients usually have a 0.5 to 2 cm solitary reddish or yellowish papule or nodule on the head, neck, or upper trunk (picture 29). Multiple lesions may also occur (picture 30). Spontaneous resolution usually occurs within a few years. (See "Juvenile xanthogranuloma (JXG)".)
Cylindroma — Cylindromas are uncommon benign adnexal tumors that have a predilection for the face and scalp of adults. Cylindromas usually occur as red-blue or blue, slow-growing solitary papules or nodules that range from a few millimeters to a few centimeters in diameter (picture 31). Multiple cylindromas are features of familial cylindromatosis or Brooke-Spiegler syndrome (picture 32) . (See "Cutaneous adnexal tumors", section on 'Cylindroma and spiradenoma'.)
Angiolymphoid hyperplasia with eosinophilia — Angiolymphoid hyperplasia with eosinophilia (ALHE, also known as epithelioid hemangioma) is an uncommon benign vascular neoplasm that typically occurs in adults. ALHE usually presents as a group of several red-brown or violaceous papules or small nodules in a localized area on the skin (picture 33) . ALHE usually occurs on the head or neck, and the ears are a particularly common location. A skin biopsy is necessary for diagnosis.
Skin cancer — Various forms of skin cancer may present as papules or nodules on the scalp. Non-healing or recurrent ulceration, skin induration, and progressive growth should raise suspicion for malignancy. Patients may develop basal cell carcinoma and squamous cell carcinoma, the most common forms of skin cancer, as well as a wide variety of less common cutaneous malignancies that can occur on the head. Examples include Merkel cell carcinoma, which often presents as a rapidly growing skin-colored or blue-red nodule (picture 34), and angiosarcoma, which often presents as bluish to violaceous nodules, macules, or patches with or without ulceration (picture 35) . A biopsy is indicated to confirm the diagnosis of skin cancer. (See "Pathogenesis, clinical features, and diagnosis of Merkel cell (neuroendocrine) carcinoma".)
Metastatic carcinoma — The scalp is a common site for cutaneous metastases of internal malignancy. Metastatic carcinoma often presents as a firm skin-colored, red, violaceous, or hyperpigmented nodule; however, other presentations, such as patches or plaques, also occur [20,21]. Ulceration may be present. A biopsy demonstrates features of the primary malignancy.
PUSTULES — Pustular eruptions on the scalp may occur as a result of infectious or noninfectious inflammatory disorders. Recognition of the associated clinical features is important for narrowing the differential diagnosis.
Folliculitis — Folliculitis is an inflammatory process of the hair follicles that most frequently occurs as a result of the invasion of microorganisms into the follicle. Patients develop inflamed follicular papules and pustules (picture 36A-B). Bacterial culture of pustules often reveals Staphylococcus aureus infection. There are also fungal and viral forms of folliculitis. (See "Infectious folliculitis".)
Kerion — Kerion is a complication of severe tinea capitis that results from an intense inflammatory reaction to the infection (picture 3). Patients develop a boggy plaque that is often studded by pustules. Purulent drainage may be present.
Dissecting cellulitis of the scalp — Dissecting cellulitis of the scalp is an uncommon form of cicatricial alopecia that presents with follicular papules, pustules, fluctuant nodules, and abscesses on the scalp (picture 37). Patients may develop permanent alopecia, scarring, and sinus tract formation. Dissecting cellulitis of the scalp most frequently occurs in young men of African descent, but is not exclusive to this population . (See "Dissecting cellulitis of the scalp".)
Folliculitis decalvans — Folliculitis decalvans is a form of cicatricial alopecia that presents with inflamed papules and pustules on the scalp and scarring alopecia (picture 38A-B). Pustules and papules are usually located at the periphery of areas of alopecia. Tufting of hairs (multiple hairs emerging from a single follicular orifice) is an additional common feature . (See "Folliculitis decalvans".)
Acne keloidalis nuchae — Pustules are a common feature of acne keloidalis, a form of scarring alopecia distinguished by the development of dome-shaped keloid-like papules and keloid-like plaques on the posterior scalp. (See 'Acne keloidalis nuchae' above and "Acne keloidalis nuchae: Pathogenesis, clinical manifestations, and diagnosis".)
Erosive pustular dermatosis of the scalp — Erosive pustular dermatosis of the scalp is a rare disorder characterized by the development of sterile pustules, erosions, and crusted plaques on the scalp that lead to scarring (picture 39) . Erosive pustular dermatosis of the scalp may occur after scalp trauma or scalp surgery. The condition primarily affects older adults.
BLISTERS AND EROSIONS — Allergic contact dermatitis, herpes zoster, and autoimmune blistering disease are examples of disorders that may cause blistering eruptions on the scalp.
Allergic contact dermatitis — Severe allergic contact dermatitis may present with erythematous patches or plaques with vesiculation or bulla formation (picture 40). Pruritus is often intense. The diagnosis may be made clinically. Patch testing is used to identify a causative allergen. (See 'Allergic contact dermatitis' above.)
Herpes zoster — Herpes zoster presents as a dermatomal eruption with localized erythema and grouped vesicles that evolve to form erosions, pustules, and crusts (picture 41A-B). Patients usually have unilateral symptoms of burning, aching, stinging, or throbbing. Symptoms can be severe. The diagnosis is usually made clinically; however, laboratory tests are available to confirm the diagnosis. (See "Epidemiology, clinical manifestations, and diagnosis of herpes zoster".)
Autoimmune blistering diseases — Autoimmune blistering diseases, such as pemphigus foliaceus, dermatitis herpetiformis, and certain types of pemphigoid, have a predilection for the scalp. Histopathologic examination and immunofluorescence studies are used for diagnosis.
Key clinical features of these diagnoses include:
●Pemphigus foliaceus – Multiple erythematous patches or plaques with superficial erosions, crusts, or scale on the scalp, face, or upper trunk (picture 16A-B) (see "Pathogenesis, clinical manifestations, and diagnosis of pemphigus", section on 'Pemphigus foliaceus')
●Dermatitis herpetiformis – Intensely pruritic papules, vesicles, erosions, and excoriations with a predilection for the elbows, forearms, knees, scalp, back, and buttocks (picture 42) (see "Dermatitis herpetiformis")
●Mucous membrane pemphigoid with skin involvement – Mucous membrane blistering and erosions; erythematous plaques with bullae on the scalp, face, or upper trunk that often heal with scarring (see "Clinical features and diagnosis of bullous pemphigoid and mucous membrane pemphigoid", section on 'Clinical features of mucous membrane pemphigoid')
●Brunsting-Perry pemphigoid – Bullae on the scalp, face, or upper trunk that heal with scarring (picture 43) (see "Clinical features and diagnosis of bullous pemphigoid and mucous membrane pemphigoid", section on 'Brunsting-Perry pemphigoid')
THICKENED SCALP — Thickening of the scalp is an uncommon clinical finding that can occur in patients with cutis verticis gyrata and lipedematous scalp.
Cutis verticis gyrata — Cutis verticis gyrata is a rare disorder in which extensive soft tissue proliferation results in an undulating appearance of the scalp that resembles the surface of the cerebral cortex (picture 44). The scalp is soft to palpation.
Cutis verticis gyrata is classified as primary essential, primary nonessential, or secondary. Primary essential cutis verticis gyrata occurs in isolation, whereas the primary nonessential form is associated with neurologic or ophthalmologic abnormalities. The most common presentation of cutis verticis gyrata is primary nonessential cutis verticis gyrata occurring in association with intellectual disability . Secondary cutis verticis gyrata results from neoplastic or inflammatory scalp conditions, genetic disorders, or systemic diseases (eg, acromegaly, myxedema, amyloidosis) . (See "Cutis verticis gyrata".)
Lipedematous scalp — Lipedematous scalp is a rare condition characterized by thickening of the subcutaneous tissue of the scalp . The condition results in a soft, spongy, or doughy quality detected during palpation. Patients may have associated symptoms of pain, paresthesias, headache, burning sensations, tenderness, or pruritus. The term lipedematous alopecia has been used to refer to similar clinical findings accompanied by alopecia.
CICATRICIAL ALOPECIA — Cicatricial (scarring) alopecia is a permanent form of hair loss that occurs as a result of irreversible damage to hair follicles. Cicatricial alopecia should be suspected when patients exhibit hair loss that is accompanied by a loss of visible follicular ostia.
There are multiple forms of cicatricial alopecia, each of which exhibits additional characteristic clinical features. The major subtypes of cicatricial alopecia are listed below with their associated clinical findings:
●Discoid lupus erythematosus – Well-demarcated inflammatory plaques with follicular plugging that develop into atrophic, dyspigmented scars (picture 45A-D) (see "Overview of cutaneous lupus erythematosus", section on 'Discoid lupus erythematosus')
●Central centrifugal cicatricial alopecia – Centrifugal progression of alopecia on the central scalp (picture 47A-B); primarily affects women of African descent (see "Central centrifugal cicatricial alopecia")
●Folliculitis decalvans – Papules, pustules, and tufted folliculitis (multiple hairs emerging from a single inflamed follicle), particularly at the periphery of patches of alopecia (picture 38A-B) (see "Folliculitis decalvans")
●Acne keloidalis nuchae – Papules pustules, dome-shaped keloid-like papules, and keloid-like plaques on the occipital scalp (picture 26) (see 'Acne keloidalis nuchae' above and "Acne keloidalis nuchae: Pathogenesis, clinical manifestations, and diagnosis")
Performance of a scalp biopsy is usually recommended to confirm the diagnosis of cicatricial alopecia. An exception is acne keloidalis nuchae, for which the distinctive clinical features (location on posterior scalp and keloid-like papules) often negates the need for a biopsy diagnosis.
Additional subtypes of cicatricial alopecia and the evaluation and diagnosis of patients with cicatricial alopecia are reviewed in detail separately. (See "Evaluation and diagnosis of hair loss".)
MARKED PRURITUS — The presence of pruritus can be a useful clue for diagnosis. Scalp pruritus may be the most prominent scalp manifestation of pediculosis capitis and is a common feature of several other scalp diseases.
Pediculosis capitis — Pediculosis capitis (head lice) is a common cause of scalp pruritus in children, but may also occur in adults. Affected patients often present with pruritus of the scalp and excoriations without an identifiable eruption. Close examination will reveal nits (lice eggs) firmly attached to hair shafts and lice (picture 48). Cervical adenopathy may be present. (See "Pediculosis capitis".)
Other disorders — Allergic contact dermatitis, atopic dermatitis, seborrheic dermatitis, psoriasis, dermatomyositis, and dermatitis herpetiformis are examples of additional scalp disorders that frequently present with pruritus. Scabies, another pruritic disorder, typically spares the scalp but may involve the scalp in young infants and immunocompromised patients (picture 49A-B). (See "Scabies: Epidemiology, clinical features, and diagnosis", section on 'Clinical manifestations'.)
CHILDREN — Many of the disorders described above can develop in children. Seborrheic dermatitis and atopic dermatitis are common scalp conditions in infants. In children, the differential diagnosis for scalp eruptions often includes tinea capitis, pediculosis capitis, allergic contact dermatitis, and psoriasis. Nevus sebaceous, juvenile xanthogranuloma, syringocystadenoma papilliferum, and Langerhans cells histiocytosis are uncommon conditions that often initially present in children.
Scalp disorders in the newborn infant are reviewed separately. (See "Skin lesions in the newborn and infant".)
SUMMARY AND RECOMMENDATIONS
●A wide variety of disorders may present with cutaneous changes on the scalp. The patient history and physical examination are important tools for diagnosis. The recognition of certain clinical features significantly narrows the differential diagnosis. (See 'Scaly patches and plaques' above and 'Plaques without scale' above and 'Papules and nodules' above and 'Pustules' above and 'Blisters and erosions' above and 'Thickened scalp' above and 'Cicatricial alopecia' above and 'Marked pruritus' above.)
●Many scalp conditions can be diagnosed based upon information obtained from the clinical evaluation alone. If the diagnosis remains uncertain, a skin biopsy is often useful. Depending on the clinical scenario, select laboratory studies may also be of value. (See 'Patient assessment' above.)