Anatomy

Anatomically, the scalp and forehead extend from the supraorbital rims anteriorly to the nuchal line posteriorly. Laterally, it extends from the frontal process of the zygoma across the zygomatic arch to the prominence of the mastoid process.

The scalp consists of five layers which can easily be remembered by the mnemonic “SCALP,” where S is skin, C is subcutaneous tissue, A is aponeurotic layer, L is loose areolar tissue, and P is pericranium (Fig. 5.1).^6,7

Fig. 5.1 Layers of the scalp: S, skin; C, subcutaneous tissue; A, aponeurotic layer; L, loose areolar tissue; and P, pericranium.

(Reproduced from TerKonda RP, Sykes JM. Concepts of scalp and forehead reconstruction. Otolaryngol Clin North Am. 1997;30:519–539.)

The outermost layer of the scalp consists of the skin and subcutaneous tissue. Contained within this layer are hair follicles, sweat glands, and fat. Connective tissue septa within the subcutaneous layer connect firmly to the underlying musculoaponeurotic layer.

Under the subcutaneous layer is the galea aponeurotica. This is a musculoaponeurotic layer that extends from the frontalis muscles anteriorly to the occipitalis muscle posteriorly. Laterally the galea continues as the temporoparietal fascia. This tissue is highly vascularized and has found great utility in reconstructive procedures about the head and neck. Anteriorly, the galea extends into the face as the superficial musculoaponeurotic system, as outlined by Mitz and Peyronie⁸ and later modified by Jost and Levet.⁹

The muscle component of this layer consists of the paired frontalis and occipitalis muscles as well as the auricular muscles laterally. The frontalis muscles originate from the galea and insert into the dermis at the level of the superciliary arch. Contraction of the frontalis causes elevation of the eyebrows and horizontal-oriented lines in the forehead. Anteriorly, the frontalis blends with the procerus, corrugator supercilii, and orbicularis oculi. The paired corrugator supercilii muscle arises from the frontal bone near the superomedial orbital rim. The muscle runs superolaterally through the fibers of orbicularis oculi and frontalis before inserting into the medial eyebrow skin. The corrugator muscle is a brow depressor, pulling the brow medially and inferiorly, producing vertical glabellar folds. The procerus muscle is a thin muscle that inserts into the glabella and lower mid-forehead. It is a brow depressor, forming horizontal nasal root creases. In the posterior scalp, paired occipitalis muscles take origin from the superior nuchal line and mastoid, inserting into the galea.

There are three auricular muscles on each side of the scalp: the anterior auricular, superior auricular, and posterior auricular muscles. They take origin from the temporalis fascia and the mastoid bone and insert into the perichondrium external ear (Fig. 5.2).

Fig. 5.2 Extrinsic muscles of the ear – anterior auricular, superior auricular, and posterior auricular muscles.

The subgaleal fascia is a loose areolar layer beneath the galea. This tissue is thin over the vertex of the skull and becomes progressively thicker in the temporoparietal region. This layer is richly vascularized and can be elevated as an independent layer for reconstructive procedures.

The deepest layer of the scalp is the pericranium. This is the periosteal layer of the calvaria. It is a thick collagenous layer with a rich blood supply that is firmly attached to the skull in the region of the sutures. The use of pericranial flaps as a reconstructive option has been well described in the literature.

Anatomy of the temporal region

The temporoparietal region consists of four distinct fascial layers with anatomic significance. The most superficial layer is the superficial temporal fascia. This layer is a direct extension of the galea. It is closely applied to the overlying skin and subcutaneous tissue, making dissection difficult. Unless care is taken, it is easy to damage the overlying hair follicles, resulting in temporal alopecia (Fig. 5.3).

Fig. 5.3 Anatomy of the temporal region.

Deep to the superficial temporal fascia is the subgaleal fascia. Contained within this easily dissected layer are the superficial temporal artery and the frontal branch of the facial nerve. Under the subgaleal fascia is the superficial temporal fat pad. Numerous large perforating veins course through this layer, making dissection somewhat difficult.

Beneath the superficial temporal fat pad is the deep temporal fascia. This is a thick fascial layer surrounding the temporalis muscle. Superiorly it fuses with the pericranium. Inferiorly, it splits into two layers at the level of the frontozygomatic suture. The superficial portion of the deep temporal fascia attaches to the lateral border of the zygomatic arch. The deep layer fuses with the medial aspect of the arch. Reflection of the superficial portion of the deep temporal fascia with a bicoronal flap allows exposure of the craniofacial skeleton without injury to the frontal branch of the facial nerve as it passes over the arch of the zygoma.

Between the two layers of the deep temporal fascia lie temporalis muscle fibers and a thin layer of fat. This fat is continuous with the buccal fat pad of the midface. The temporalis muscle originates from the temporal fascia and inserts on to the coronoid process of the mandible. It is supplied by two deep temporal branches of the internal maxillary artery: the middle and deep temporal arteries.

Blood supply

The scalp and forehead have a rich vascular plexus supplied by branches of both the internal and external carotid arteries. The supraorbital and supratrochlear arteries are terminal branches of the internal carotid arteries, providing the blood supply to the forehead and anterior scalp. The superficial temporal artery, posterior auricular, and occipital arteries are branches of the external carotid artery. These vessels supply the lateral and posterior aspects of the scalp. The extensive interconnection between each of the angiosomes allows replantation of the entire scalp based on a single donor vessel. The venous system parallels the arterial supply, eventually draining into the external and external jugular veins (Fig. 5.4).

Fig. 5.4 Arterial and nervous supply of the scalp.

Nerves

The frontal branch of the facial nerve supplies the motor innervation of the forehead. The nerve emerges from the parotid 2.5 cm anterior to the tragus. It ascends above the periosteum over the central portion of the zygomatic arch, passing 1.5 cm lateral to the orbital rim to innervate the frontalis muscles on their deep surfaces. It courses along the deep surface of the superficial temporal fascia, putting it at risk for injury with dissection into the temporal region (Fig. 5.5). The posterior auricular branch of the facial nerve supplies the occipitalis muscle. This branch originates with the facial nerve as it exits the stylomastoid foramen. The temporal muscles are supplied by the posterior and anterior deep temporal nerves, which are branches of the trigeminal nerve. This dichotomy of innervation is used successfully in developing reanimation procedures for patients with facial palsy.

Fig. 5.5 Course of the frontal branch of the facial nerve. Left, histologic cross-section at the level of the zygomatic arch. Right, schematic illustration depicting the fascial planes of the cheek and temporal region. SMAS, superficial muscular aponeurotic system.

(Reproduced from Agawal CA, Mendenahall SD, Foreman KB, et al. Plast Reconstr Surg. 2102;125:532–537.)

The supratrochlear and supraorbital nerves, branches of the first division of the trigeminal nerve, provide sensation to the forehead and anterior scalp. The supratrochlear nerve exits the orbit between the pulley of the superior oblique and the supraorbital foramen. It ascends beneath the corrugator supercilii to supply the medial forehead, upper eyelid, and conjunctiva. The supraorbital nerve exits the frontal bone through the supraorbital foramen before dividing into two branches. The superficial branch of the supraorbital nerve courses over the surface of the frontalis muscle to provide sensation to the central forehead. The rest of the scalp and top of the head are innervated by the deep branch, which travels laterally between the periosteum and the galea. Knize¹⁰ has described the anatomy of the deep branch of the supraorbital nerve. The deep branch runs in a 1-cm-wide band medial to the palpable temporal crest line to innervate the frontoparietal scalp (Fig. 5.6).

Fig. 5.6 The course of the deep branch of deep (SON-D) and superficial (SON-S) division of the supraorbital nerve. The deep branch superiorly or obliquely across the forehead between the galeal aponeurotica and the periosteum and by the midforehead level found between 0.5 and 1 cm medial to the superior temporal crest. It pierces the galea just before the coronal suture (CS). The superficial branch passes through the lower frontalis muscle to run over the surface of the muscle. TBr, terminal branch; STL, superior temporal line of the skull.

(Reproduced from Knize DM. A study of the supraorbital nerve. Plast Reconstr Surg. 1995;96:564–569.)

The zygomaticotemporal nerve, a branch of the maxillary division of the trigeminal nerve, supplies the skin just lateral to the temporal crest. The auriculotemporal nerve, a branch from the third division of the trigeminal nerve, supplies the ear and lateral scalp.

The greater occipital nerve is a spinal nerve that arises between the first and second cervical vertebra along with the lesser occipital nerve. It emerges from the suboccipital triangle 3 cm below the occipital protuberance and 1.5 cm lateral to the midline to supply the posterior part of the scalp to the vertex.

Aesthetic units of the scalp and forehead

Gonzalez-Ulloa¹¹ first conceived the idea of aesthetic units of the face. Facial aesthetic units and subunits are visual anatomic boundaries formed by contour changes in facial topography. Making incisions along these boundaries or replacing entire subunits hides scars in the light reflections and shadows of the face. The aesthetic subunits of the face must be respected when planning reconstructive procedures of the head and neck.

The upper third of the face historically has been subdivided into five units: two temporal units posterior to the anterior temporal crest, a central forehead unit (Fig. 5.7), and two eyebrow units along the supraorbital rims. More recently, the forehead has been subdivided into paramedian, lateral, and lateral temporal subunits.¹² Care must be taken not to cause inadvertent displacement of mobile subunits such as the brow when operating on the forehead or scalp.

Fig. 5.7 Aesthetic units of the forehead region. a, central forehead unit; b, bilateral temporal units; c, two eyebrow units.

The hair-bearing scalp is its own aesthetic unit. Strict attention to the re-establishment of the temporal and anterior hairline can prevent unwanted secondary deformities.

Hair structure and cycle

Hair is the most visible feature of scalp anatomy. Hair has two separate structures: the follicle in the subcutaneous tissue and the shaft that we see. Of the human body’s 5 million hair follicles, approximately 100 000 are present in the scalp.

Human hair is composed primarily of keratin. The visible hair shaft is dead. It is the proteinaceous end product of a living structure called the hair matrix contained within the subcutaneous tissue. Viable cells in the base of the matrix proliferate rapidly. Immediately above this area of cell division is the zone of keratinization. Cells in this zone undergo a process of dehydration and chemical change creating the dense, cohesive mass of keratinization forming the hair shaft. As new keratinized cells are added to the base of the hair shaft, the hair grows. Scalp hair grows 0.35 mm/day; however this can vary with age, nutrition, pregnancy, and environmental factors.

The follicle is an oval-shaped structure containing several different layers.¹² At the base of the follicle is the papilla. It contains capillary loops that perfuse the growing hair follicle. Hair growth requires diffusion of oxygen and nutrients from the vascular network of the papilla. The hair bulb caps the papilla to form a bulbous expansion that forms the hair shaft.

Under the influence of the dermal papilla, epidermal cell differentiation produces keratinized hair fibers. The matrix cells differentiate to form the hair cortex and surrounding hair cuticle. In the center of the hair shaft are large polygonal cells called the medulla. Cells that surround the hair shaft comprise the inner root sheath (IRS). The IRS consists of three distinct histological layers: the cuticle, Huxley layer, and Henley layer. Above the level of the attached sebaceous gland, the IRS breaks down to form on the hair cortex and surrounding cuticle to protrude above the epidermis.

The outer root sheath (ORS) is distinct from other epidermal components of the hair follicle, being continuous with the epidermis. In the “bulge” region of the hair follicle, an arrector pili muscle spans between the ORS and epidermis. Contraction of this muscle makes hair stand erect and produces “goosebumps” in the skin when subjected to cold. The “bulge” region is believed to be the storage area for hair follicle stems cells.

Also extending from the ORS is the sebaceous gland. It consists of specialized cells focused on the production of lipids. The products of the sebaceous gland are believed to break down the IRS. The ORS surrounds the hair fiber and IRS. Just above the bulb region containing the dermal papilla, the ORS tapers and ends. Thus, the ORS does not entirely cover the hair fiber and IRS.

There are two basic types of normal postnatal human hair. Vellus hair is fine, soft, short, hypopigmented, unmedullated, and almost invisible. It covers the forehead and bald scalp. Terminal hair of the scalp, beard, and eyebrows is relatively coarse, long, often medullated, and variably pigmented. Some vellus hairs become terminal hairs, as in beard development in adolescent males. Additionally, terminal hairs can become vellus hairs, as in androgenetic alopecia. Testosterone and dihydrotestosterone can reduce in vitro proliferation of dermal papilla cells and ORS keratinocytes from the frontoparietal scalp.

The matrix of all hair follicles undergoes cycles of growth and degeneration (Fig. 5.8). The hair cycle has three stages of growth: anagen (growing phase), catagen (involutional phase), and telogen (dormant phase). At any one time, 90–95% of hairs are in the anagen phase, 5–10% are in catagen, and 1–2% is in telogen. The growing phase of human hair lasts about 1000 days. Catagen occurs for 2–3 weeks and telogen for 2–3 months. Up to 100 telogen hairs are lost from the scalp per day, an amount approximating the number of hairs entering anagen per day.

Fig. 5.8 The hair cycle. The stages of the hair cycle are illustrated beginning from the first postnatal anagen. Follicles progressing through a destructive phase (catagen) during which the lower two-thirds of the follicle undergoes degeneration. After the resting phase (telogen), stem cells become activated to form a new growing follicle (anagen).

(Reproduced from Fuchs E. Scratching the surface of skin development. Nature. 2007;445:834–842.)

Cicatricial alopecia

Cicatricial alopecia is characterized by scarring of the scalp with resultant hair loss. It is caused by a number of pathologic conditions.^13,14 The end result however is always the same: stem cell failure at the base of the follicle, inhibiting follicular recovery from the telogen phase. It can be classified into five categories: congenital, autoimmune, neoplastic, infective, and acquired. A complete discussion regarding each of these conditions is not within the remit of this article, Highlighted conditions of special interest to the practicing surgeon will be discussed (Table 5.1).

Table 5.1 Etiology of cicatricial alopecia

Aplasia cutis congenita (ACC)

This condition was first described in 1176. Since then, more than 500 patients with this condition have been described in the literature. It is a rare congenital defect of the skin and subcutaneous tissue of the scalp. Less commonly, it can involve the periosteum, bone, and dura of the infant scalp.^12,13 The scalp is the most common location for ACC. It is involved in 65% of all patients presenting with the disease. At birth these defects are usually covered with a thin fragile transparent membrane (Fig. 5.9). In older children, there is usually a hairless patch within the scalp resembling an atrophic scar. Less frequently, the lesions are found on the arms, knees, trunk, lower limbs, and face. Some patients with ACC also suffer from additional terminal transverse limb anomalies, nail hypoplasia, omphalocele, cardiovascular and central nervous system abnormalities.

Fig. 5.9 Aplasia cutis congenita: a 10-year-old boy with thin atrophic scar of the scalp that was allowed to heal by secondary intention.

(Copyright © The Regents of the University of California, Davis campus. Originally published in Dermatology Online Journal All rights reserved. Used with permission.)

The etiology is unclear. Hypotheses include a malformation of the neural tube or mechanical disruption of the skin in utero. Vascular accident, direct pressure, and amnionic bands have been advanced as etiologic factors. Most of the cases appear to be sporadic; however an autosomal-dominant inheritance pattern has been described. Maternal exposure to methimazole and carbimazole may contribute to the development of ACC.

Wound treatment in patients with superficial ulceration is generally conservative with regular dressing changes. Larger defects, especially with underlying bone defects, are susceptible to infection, meningitis, sagittal sinus thrombosis, and hemorrhage. In these deeper lesions, dural reconstruction, cranioplasty, and flap reconstruction may prove life-saving.^15,16

Nevus sebaceous of Jadassohn (sebaceous nevus)

Jadassohn first described nevus sebaceum in 1895.¹⁷ It is a well-circumscribed yellow or orange lesion that occurs mainly on the face and scalp of infants. Of newborns, 0.3% are affected by nevus sebaceous. It occurs with equal frequency in males and females of all races. Clinically, the lesion presents as a solitary hairless patch noted at birth (Fig. 5.10). At puberty, they can become raised, thickened, and nodular.¹⁸

Fig. 5.10 Nevus sebaceous of Jadassohn. Note the orange hairless patch in this infant’s scalp.

Histologically, it is a hamartomatous lesion consisting of predominantly sebaceous glands, abortive hair follicles, and ectopic apocrine glands. The entity is important to recognize, because of its propensity for malignant degeneration. Malignant transformation occurs in 10–15% of lesions in some series.¹⁹ The most common malignant neoplasm arising in this disorder is basal cell carcinoma. The most frequent benign tumor is trichoblastoma. Other benign and malignant tumors include syringocystadenoma papilliferum arising from the apocrine sweat glands, keratoacanthoma, apocrine cystadenoma, leiomyoma, and sebaceous cell carcinoma. Rarely, malignant eccrine poroma and apocrine carcinomas have been reported.

Nevoid basal cell carcinoma syndrome (NBCCS)

This is an autosomal-dominant condition associated with the development of multiple basal cell carcinomas of the skin (Fig. 5.11). First described by Gorlin and Goltz in 1960,²⁰ it is an inherited disorder involving defects within multiple organ systems including the skin, skeletal system, endocrine and nervous system. To be diagnosed with the disorder, patients must meet two major criteria or have one major and two minor criteria (Table 5.2).^21,22

Fig. 5.11 Nevoid basal cell carcinoma syndrome: multiple basal cell carcinomas associated with palmar pits and jaw cysts.

Table 5.2 Nevoid basal cell carcinoma syndrome (NBCCS)

The condition is caused by a mutation of the PTCH (patched) gene found on chromosome arm 9q. It has complete penetrance and variable expressivity. About a third of patients are new mutations.

Patients should be aware of the need for limiting ultraviolet exposure and the requirement for sunscreen. Basal cell carcinomas require frequent follow-up to achieve early diagnosis and treatment. Treatment of patients with NBCCS involves surveillance for the treatment of associated conditions (odontogenic cysts, ovarian fibromas, medulloblastoma) and treatment of multiple basal cell carcinomas. This often requires complex repairs, skin grafts, or flaps.

Xeroderma pigmentosum (XP)

XP is an autosomal-recessive disorder characterized by intolerance of the skin to ultraviolet light. It has a prevalence of 1/250 000 in the US.²³ Certain populations have a higher prevalence. For example, in Japan the prevalence is estimated at 1/40 000. The disease is due to the inability of the individuals affected with this disorder to repair damaged induced by sunlight to their DNA. Normally, damaged segments of DNA are excised and replaced with new sequences of bases. The most common defect in XP is an autosomal-recessive defect in which nucleotide excision repair (NER) enzymes are mutated, leading to a reduction in NER. Left unchecked, damage caused by ultraviolet light causes mutation in individual cell DNA. Seven XP repair genes, XPA through XPG, have been identified. These entities occur with varying frequencies, with XPA being the most common mutation. There is also an XP variant that has been described. The defect in this condition is not in NER, but is instead in postreplication repair. In XP variant, a mutation occurs in DNA polymerase (Fig. 5.12).

Fig. 5.12 Young patient with xeroderma pigmentosum. Note the freckling, crusts, and hypopigmentation in sun-exposed areas.

There is no cure for XP. The DNA damage is cumulative and irreversible. As a result these patients develop multiple epithelial malignant neoplasms at an early age, most frequently in sun-exposed parts of the body. Tumors include squamous cell carcinoma, basal cell carcinomas, malignant melanoma, and fibrosarcoma. Two of the most common causes of death for XP patients are metastatic melanoma and squamous cell carcinoma.

Ocular problems occur in nearly 80% of patients with XP. These include photophobia, conjunctivitis, symblepharon, ectropion, and cutaneous malignancies.

Management is limited to avoidance of exposure to damaging ultraviolet radiation. This includes sunscreen, protective clothing, and sunglasses. Regular surveillance for treatment of neoplasms is very important. Gene therapy for XP is still in a theoretical and experimental stage. Various methods of correcting the defects in XP have been attempted using viral vectors carrying the gene replacement products.

Giant hair nevus – congenital nevomelanocytic nevus (CNN)

CNN, commonly called the congenital hairy nevus, is a pigmented surface lesion present at birth.^24,25 It is composed of neveomelancocytes, derivatives of melanoblasts. They are classified into three groups: small (<1.5 cm), medium (1.5–19.5 cm), and large (>20 cm in adolescents and adults or predicted to reach 20 cm by adulthood). CNN expands with growth of the child. The risk of melanoma development is proportional to the size of the congenital nevus (Fig. 5.13).

Fig. 5.13 Giant hairy nevus involving the forehead, temporal region, and eyelids of a young girl.

The potential for large congenital nevi to become malignant has been variously debated in the literature. Lifetime rates have varied from 6 to 12%. In large nevi, 50% of malignancies develop by age 5, 60% by childhood, and 70% by puberty. Approximately 40% of malignant melanomas observed in children occur in large congenital nevi. Malignancy should be suspected with focal growth, pain, bleeding, ulceration, and significant pigmentary change.

Prophylactic excision remains the mainstay of treatment. Surgical removal has two goals: first, to improve the cosmetic appearance of the patient; and second, to reduce the likelihood of malignant transformation. Surgical treatment is typically begun at 6 months of age and usually requires a number of stages. Treatment consists of serial excision, skin grafting, tissue expansion, rotation flaps, and free tissue transfer. Cultured epidermal autografts and dermal regenerate templates have been used successfully after excision of giant hairy nevi.

Dysplastic nevus

Dysplastic nevi are compound nevus with cellular and architectural dysplasia. They can be flat or raised and vary in size, but are typically larger than normal compound nevus (5–15 mm) with lack of pigment uniformity. Atypical moles may appear anywhere on the body, but most frequently occur on the scalp, chest, back, and buttocks. They may occur in sun-exposed and sun-protected areas. Atypical moles can be inherited or sporadic. The prevalence of atypical moles in white populations has been reported to be as high as 10%. Familial atypical moles may be inherited as an autosomal-dominant trait. This familial form of dysplastic nevi is known as familial atypical mole and melanoma syndrome (FAMMM) (Fig. 5.14).^26,27

Fig. 5.14 (A, B) Familial atypical mole and melanoma syndrome (FAMM). Previously called dysplastic nevus syndrome, FAMM combines a family history of melanoma with multiple atypical nevi.

Melanoma can develop from atypical moles. The exact risk of an individual nevus transforming into a melanoma is thought to be 1 in 200 000. Patients with numerous atypical moles are at higher risk of developing melanoma than those individuals with only a few atypical moles. The risk is more pronounced with a family history of melanoma. The lifetime risk of melanoma may approach 100% in individuals with FAMMM.

Patients with atypical nevi should undergo yearly cutaneous exam with serial color photography of suspicious lesions. Changing lesions or nevi suspicious for melanoma should be removed with narrow margins. Shave biopsy should be avoided in any pigmented lesion because it does not provide the necessary depth information. Wider excision may be indicated after interpretation of the lesion.

Linear scleroderma – en coup de sabre

En coup de sabre is a form of localized linear scleroderma that primarily affects the forehead of affected pediatric patients. It appears as an indented, vertical, colorless line of skin. Its appearance to some resembles a deep saber wound. It is a rare disease of uncertain causation that is characterized by progressive craniofacial focal atrophy.²⁸ The active stage usually lasts 3–5 years. Involutionary atrophy of skin, muscle, and even bone may occur. Various ophthalmological and neurologic abnormalities have been observed in patients with linear scleroderma en coup de sabre, including seizures and cranial nerve palsies. The distinction between linear scleroderma en coup de sabre and Parry–Romberg syndrome is unclear. Parry–Romberg syndrome is characterized by a gradual progressive facial hemiatrophy. In full-fledged cases, there is a significant deformity, with one side of the face smaller than the other. This is in sharp contrast to typical linear scleroderma en coup de sabre, where the abnormality is confined to the forehead (Fig. 5.15).

Fig. 5.15 Linear scleroderma – en coup de sabre. A 54-year-old woman with a 3-year history of progressive depigmentation and indentation of the forehead and scalp.

The etiology is unknown. The most widely accepted theory is that the condition represents an autoimmune phenomenon directed at ectodermal derivatives of the forehead and scalp. Others invoke infective or genetic factors as possible mechanisms of action.

The management is unsatisfactory. Various therapeutic modalities (topical and pharmacologic agents, immunosuppression, and phototherapy) have been attempted, none with great success. Most require soft-tissue augmentation using microsurgical techniques once the condition has stabilized.²⁹

Discoid lupus erythematosus (DLE)

DLE is a chronic skin condition that appears as a red inflamed patch with a scaling and crusting appearance. The center may appear lighter in color with a rim darker than the normal skin. There is a predilection for the face, scalp, and ears; however other regions of the body can be affected. When lesions occur in hairy areas such as the beard or scalp, permanent scarring and hair loss can occur (Fig. 5.16).^30,31 DLE may occur in patients with systemic lupus erythematosus (SLE) and some patients (<5%) with DLE progress to SLE.

Fig. 5.16 (A, B) Discoid lupus erythematosus causing widespread scarring alopecia.

The pathophysiology of DLE is not well understood. It has been suggested that ultraviolet light induces the production of a heat shock protein. The protein then acts as a target for the host’s T-cell-mediated immunity.

The condition is more common in African Americans than whites or Asians. It is more prevalent in woman than men. It most often affects patients between 20 and 40 years of age.

Therapy with sunscreens, topical steroids, topical calcineurin inhibitors, imiquimod, and antimalarial agents is usually effective. Occasionally immunosuppressives may be indicated. Surgical excision for burned-out areas of scarring has been attempted, occasionally followed by recurrence in the scar.

Cutaneous sarcoidosis

Sarcoidosis is a multisystem disease of unknown cause that may involve virtually any organ system. It is often called the great imitator. Cutaneous sarcoidosis has many morphologic presentations and often mimics other dermatologic diseases. Cutaneous involvement occurs in 20–35% of patients with systemic sarcoidosis but may also occur without systemic involvement.

Most authors divide lesions of cutaneous sarcoidosis into nonspecific and specific types based on the presence or absence of noncaseating granulomas on biopsy. In nonspecific lesions, no granulomas are found. Specific lesions display noncaseating granulomas.

Lupus pernio is one of the few cutaneous manifestations that are characteristic of sarcoidosis. Lesions appear as indurated plaques that affect the midface, particularly the alar rim of the nose. Lesions of cutaneous sarcoidosis can also appear in pre-existing scars. This condition is called scar sarcoidosis. Therefore, sarcoidosis should be considered in the differential diagnosis of an enlarging, previously inactive scar. Often the lesion is mistaken for a keloid. Sarcoidosis of the scalp can result in scarring and nonscarring alopecia (Fig. 5.17). It is often mistaken for DLE, lichen planopilaris, and scleroderma. Local destruction and scarring of follicles in sarcoidosis may lead to permanent alopecia.^32,33

Related posts:

Technology innovation in plastic surgery Cleft and craniofacial orthognathic surgery Managing the cosmetic patient TMJ dysfunction and obstructive sleep apnea Fractures and dislocations of the wrist and distal radius Facial transplant

Stay updated, free articles. Join our Telegram channel

Join