Section 11. Benign Dermal Proliferations

Connective tissue nevi are benign, slightly elevated, well-circumscribed plaques that are often seen as an isolated skin finding, but can also be associated with other systemic disease (Table 11-1).

Synonyms Nevus elasticus, juvenile elastoma, collagenoma, collagen hamartomas.

Epidemiology

Age Present at birth or childhood.

Gender M = F.

Prevalence Uncommon.

Genetics May have an autosomal dominant inherited form. Buschke-Ollendorf syndrome has mutation in the LEMD3 gene.

Pathophysiology

Connective tissue nevi are localized malformations of dermal collagen and/or elastic fibers.

History

Connective tissue nevi appear in childhood or adolescence and are asymptomatic but can be disfiguring.

Physical Examination

Skin Findings

Type Slightly raised plaque (Fig. 11-1).

Color Flesh-colored to yellow.

Size Few millimeters to several centimeters.

Number Solitary or multiple.

Distribution Symmetrically over abdomen, back, buttocks, arms, thighs.

General Findings

Can be associated with systemic disease (Table 11-1).

Differential Diagnosis

Connective tissue nevi can be diagnosed clinically and confirmed by skin biopsy. They can be confused with other dermal or subcutaneous processes such as fibromatoses, fibrous hamartoma of infancy, infantile myofibromatosis, dermatofibromas, lipomas, scars, keloids, pseudoxanthoma elasticum, or mucopolysaccharidoses.

Laboratory Examinations

Dermatopathology Skin biopsy reveals disorganized collagen and/or elastin fibers. Typically, there is an increase in collagen and a decrease or normal amount of elastin. Biopsies of the lesion can be easily mistaken for normal skin.

Course and Prognosis

Connective tissue nevi are benign. They persist for life and can increase in number during pregnancy. They are typically asymptomatic but can be cosmetically troublesome. The presence of connective tissue nevi should alert the clinician to check carefully for other signs of tuberous sclerosis (Table 11-1).

Management

Treatment for connective tissue nevi is not necessary. Early recognition and evaluation for possible associated syndromes (Table 11-1), such as tuberous sclerosis, is recommended. Cosmetically, the lesions tend to be too large yet subtle to warrant treatment. Cosmetic improvement can be attempted by surgical excision, dermabrasion, electrosurgery, curettage, and laser ablation.

Becker’s nevus is a common acquired benign hamartoma that occurs as a unilateral brown pigmented plaque, typically on the shoulder of adolescent boys. Over time, the lesion becomes hairy and may become slightly raised.

Synonyms Becker’s melanosis, Becker’s pigmentary hamartoma, nevoid melanosis, pigmented hairy epidermal nevus.

Epidemiology

Age 50% before 10 years, 25% between 10 and 15 years, and 25% after 15 years.

Gender M > F, 6:1.

Incidence 0.5% in adolescent males. Incidence much less in females.

Etiology Hamartoma of mesoderm and ectoderm tissues.

Genetics May be familial in some cases, heighten sensitivity to androgens.

History

Becker’s nevi are thought to have an increased number of androgen receptors which would account for its onset at/around puberty and the clinical appearance of smooth muscle thickening with hypertrichosis, hypertrophic sebaceous glands, and acne.

Physical Examination

Skin Findings

Type Isolated macule or plaque, smooth or verrucous surface, increased hair growth (in 56%, Fig. 11-2).

Color Flesh-colored to tan to brown, blotchy.

Size One to several centimeters (average size approximately 125 cm).

Shape Large, irregular shape.

Number Typically solitary, may be multiple.

Distribution Unilateral on shoulder (32%), lower back (23%), upper back (19%), arms (3%), legs (3%).

Side-Lighting Oblique lighting of the lesion will help to detect subtle elevation.

General Findings

Associated findings are uncommon. In rare instances, underlying hypoplasia of the tissue may be present (i.e., shortened extremity).

Differential Diagnosis

The diagnosis of a Becker’s nevus is often made by history and clinical examination. The increased hair growth (seen in 56% and predominantly in males) is distinctive for Becker’s nevi. Becker’s nevi can be confused with café au lait macules, congenital nevi, plexiform neurofibromas, or congenital smooth muscle hamartomas.

Laboratory Examinations

Dermatopathology Epidermal papillomatosis, acanthosis, hyperkeratosis, and occasional horn cysts. No nevomelanocytes are present. Melanocyte numbers are not increased. Basal cell keratinocytes are packed with melanin. Occasionally, a concomitant smooth muscle hamartoma may be seen.

Course and Prognosis

Pigmentation occurs in adolescence usually followed by increased coarse hair growth (56%) in affected males. Females with Becker’s nevi have less of a tendency to have hair growth in the lesion. After 2 years, the lesion stabilizes and may fade slightly but persists for life. They may be associated with a smooth muscle hamartoma. They are typically asymptomatic, but may be pruritic. Becker’s nevi are benign and malignant transformation has not been reported. Very rarely, Becker’s nevi can have an associated underlying anomalies: hypoplasia of the ipsilateral breast, arm, lumbar spina bifida, thoracic scoliosis, pectus carinatum, enlargement of the ipsilateral foot.

Management

Becker’s nevi are benign and thus no treatment is necessary. Lesions tend to be quite large and treatment becomes impractical. Cosmetically, lesions can be lightened or the hair can be removed with laser therapy, but recurrence rates are high, and frequent treatments may be necessary. Patients with Becker’s nevi should also be examined for the rare associated soft tissue or bony abnormalities.

Recurrent infantile digital fibromas are single or multiple fibrous nodules occurring on the fingers and toes, during infancy, or early childhood.

Synonyms Infantile digital fibromatosis, Reye’s tumor, inclusion body fibromatosis.

Epidemiology

Age At birth or during the first years of life.

Gender M = F.

Etiology Unknown.

Pathophysiology

Immunohistochemical and ultrastructural studies have shown that the fibroblasts contain myofilaments. Eosinophilic inclusions are suggestive of a possible viral etiology.

Physical Examination

Skin Findings

Type Nodules (Fig. 11-3).

Size Few millimeters to 2 cm.

Color Flesh-colored to pink.

Number Solitary and multiple.

Palpation Firm.

Distribution Dorsolateral aspects of fingers or toes. Thumbs and great toes usually spared.

Differential Diagnosis

History, physical examination, and skin biopsy can differentiate recurrent digital fibromas from verrucae, periungual fibromas, supernumerary digits, fibroepithelial polyps, or other dermal proliferations.

Laboratory Examinations

Dermatopathology Skin biopsy reveals many spindle cells and collagen bundles arranged in interlacing fascicles in the dermis. The cells contain characteristic perinuclear eosinophilic inclusions measuring 3 to 10 μm in diameter (collection of actin microfilaments by ultrastructural studies).

Course and Prognosis

The lesions of recurrent infantile digital fibromas appear in infancy and spontaneous involution may occur after several years.

Management

For smaller asymptomatic lesions, no treatment is necessary and spontaneous regression is possible. Larger lesions can lead to functional impairment or deformity. For cosmetic and functional purposes, removal of these lesions by surgical excision can be performed. In 75% of cases, recurrences are observed in late childhood, at which time wide surgical excision may be required.

Rudimentary supernumerary digits are soft-tissue reduplicates that typically occur on the lateral sides of normal digits.

Synonyms Rudimentary polydactyly.

Epidemiology

Age At birth.

Gender M = F.

Race Black > white 10:1.

Prevalence 1 per 1000 in whites, 10 per 1000 in blacks.

Genetics AD inheritance.

Pathophysiology

Most cases of rudimentary supernumerary digits occur as an isolated AD inherited malformation. Rarely, they may be manifestations of a larger intrauterine growth that may have been amputated.

Physical Examination

Skin Findings

Type Papules, nodules.

Size Few millimeters to 2 cm.

Color Flesh-colored.

Other May contain cartilage or vestigial nail.

Distribution Bilateral. Most common: ulnar side of the fifth digit (Fig. 11-4).

Differential Diagnosis

Family history and the bilateral, symmetric appearance of rudimentary supernumerary digits can differentiate them from recurrent digital fibroma, verrucae, periungual fibromas, fibroepithelial polyps, or other dermal proliferations.

Laboratory Examinations

Dermatopathology Skin biopsy reveals fascicles of nerve fibers. May contain cartilage or vestigial nail.

Course and Prognosis

Rudimentary supernumerary digits are present at birth and persist for life. Most are asymptomatic, but some can be painful. They are benign and not associated with any systemic abnormalities.

Management

For smaller asymptomatic lesions, no treatment is necessary. For larger and/or painful lesions, surgical removal is recommended. Attempts at removal should encompass the base of the lesions since residual papules at the site may lead to painful neuromas later in life.

Hypertrophic scars and keloids are formed when there is an exaggerated fibrous tissue response to cutaneous injury. A hypertrophic scar remains confined to the site of original injury; a keloid, however, extends beyond this site with clawlike extensions.

Insight

Hypertrophic scars and keloids can be very refractory to treatment and may arise seemingly spontaneously in predisposed individuals.

Epidemiology

Age Puberty to 30 years of age.

Gender M = F.

Race Much more common in darker skin types.

Etiology Unknown. Usually follow injury to skin (i.e., surgical scar, laceration, abrasion, cryosurgery, electrocoagulation, as well as vaccination, acne, etc.). May also arise spontaneously without history of injury.

History

Scars or keloids appear and are usually asymptomatic. May be pruritic or painful at onset. Symptoms fade with time.

Physical Examination

Skin Findings

Type Papules, nodules (Fig. 11-5).

Color Flesh-colored to pink.

Shape May be linear. Hypertrophic scars: dome-shaped, confined. Keloids extend clawlike beyond the site.

Palpation Firm to hard; surface smooth.

Sites of Predilection Ear lobes, shoulders, upper back, chest.

Differential Diagnosis

The diagnosis of a hypertrophic scar or keloid is made clinically. A biopsy is usually not warranted unless there is clinical doubt, because it may induce new hypertrophic scarring or keloid formation. The differential diagnosis includes a dermatofibroma, dermatofibrosarcoma protuberans, desmoid tumor, sarcoidosis, foreign body granuloma, or lobomycosis.

Laboratory Examinations

Dermatopathology A hypertrophic scar appears as whorls of young fibrous tissue and fibroblasts in haphazard arrangement. A keloid has an added feature of thick, eosinophilic, acellular bands of collagen.

Course and Prognosis

Hypertrophic scars tend to regress in time becoming flatter and softer. Keloids, however, may continue to slowly expand in size for years.

Management

A person with a history of hypertrophic scars and/or keloids should avoid skin trauma and elective procedures (e.g., ear piercing) to reduce the risk of scar formation. Once formed, the treatment for hypertrophic scars and keloids include topical steroids with or without occlusion (flurandrenolide-impregnated tape), intralesional steroids (triamcinolone (3–40 mg/mL, intralesional 0.1–1 mL q6 weeks) often reduces pruritus or sensitivity of lesion, as well as reducing its volume and flattening it. Combined treatment of intralesional triamcinolone and cryotherapy may be a little more effective. Lesions that are excised surgically often recur larger than the original lesion. Thus, careful plastic surgery and occlusive wound care is recommended if excision is to be attempted.

Dermatofibromas are very common, benign, dimpling skin lesions, usually occurring on the extremities, important only because of their cosmetic appearance or their being mistaken for other lesions.

Synonyms Solitary histiocytoma, sclerosing hemangioma, histiocytoma cutis, fibroma simplex, benign fibrous histiocytoma, nodular subepidermal fibrosis, dermal dendrocytoma.

Epidemiology

Age Occasionally seen in children, more common in adolescence and adulthood.

Gender F > M.

Etiology Unknown, may be chronic histiocytic–fibrous reaction to insect bite, skin injury, or ingrown hair.

Physical Examination

Skin Findings

Type Papule or nodule (Fig. 11-6).

Size 3 to 10 mm in diameter.

Color Flesh-colored, pink, brown, tan, dark brown.

Palpation Firm.

Number Usually solitary, may be multiple.

Dimple Sign Lateral compression with thumb and index finger produces a depression or dimple known as the “Fitzpatrick sign.”

Distribution Legs > arms > trunk. Uncommonly occur on head, palms, soles.

Differential Diagnosis

Dermatofibromas are diagnosed clinically and the dimpling sign is a useful clinical diagnostic tool. Dermatofibromas may be confused with nevi, scars, cysts, lipomas, or histiocytomas.

Laboratory Examinations

Dermatopathology Skin biopsy shows a proliferation of spindle-shaped fibroblasts/collagen fibers and/or histiocytes. Thick, hyalinized collagen bundles seen at the periphery and the overlying epidermis are usually hyperplastic with flat confluent rete ridges and hyperpigmentation of the basal layer.

Immunohistochemistry Positive for vimentin, factor XIIIa, muscle-specific actin, and histiocytic markers such as KP-1 and HAM-56. Negative for CD-34.

Course and Prognosis

Lesions appear gradually over several months and persist for years to decades; few lesions regress spontaneously.

Management

Dermatofibromas are benign and typically best left untreated. Surgical removal is not usually indicated because the resulting scar is often worse cosmetically. Indications for excision include repeated trauma, unacceptable cosmetic appearance, or uncertainty of clinical diagnosis. Cryotherapy may be used to flatten raised lesions.

A skin tag is a benign, pedunculated lesion the color of the skin or darker, occurring at intertriginous sites.

Insight

Although totally benign, skin tags can be associated with acanthosis nigricans and, in this context, can suggest an underlying malignancy or insulin-resistant state.

Synonyms Acrochordon, cutaneous papilloma, soft fibroma, fibroepithelial polyp.

Epidemiology

Age Adolescence and adulthood.

Gender F = M.

Incidence 50% of all adults have at least one skin tag.

Etiology Unknown. Often familial. More common in overweight individuals.

History

Usually asymptomatic, but skin tags may become inflamed or irritated. Occasionally, they may become tender or bleed following trauma or torsion.

Physical Examination

Skin Findings

Type Pedunculated papules (Fig. 11-7).

Size 1 to 2 cm.

Color Flesh-colored or darker.

Shape Usually round to oval.

Number One to several.

Palpation Soft, pliable.

Distribution Intertriginous areas.

Sites of Predilection Neck, axillae, inframammary, groin, eyelids.

Differential Diagnosis

The diagnosis of skin tags is typically made clinically. The differential diagnosis includes a pedunculated dermal or compound melanocytic nevus, neurofibroma, seborrheic keratosis, or wart.

Laboratory Examinations

Dermatopathology Skin biopsy shows a pedunculated lesion of dense collagenous stroma with thin-walled dilated blood vessels in the center.

Course and Prognosis

Skin tags tend to become larger and more numerous over time. They are benign and asymptomatic, but on occasion can torse with ensuing infarction and autoamputation.

Management

Skin tags are benign thus no treatment is necessary. Symptomatic skin tags can be removed by snipping them off with scissors, electrodesiccation, or cryosurgery.

Leiomyomas are benign dermal tumors arising from the smooth muscle cells of the arrectores pilorum which are clinically characterized by solitary or multiple red dermal nodules subject to episodes of paroxysmal pain.

There are three types of leiomyomas:

1. Piloleiomyoma: solitary from the arrector pili muscles or multiple with AD inheritance.

2. Genital leiomyomas: from the dartoic, vulvar, or mamillary muscles of the scrotum, labia, or nipple.

3. Angioleiomyomas: arising from vascular smooth muscle.

Synonyms Leiomyoma cutis, superficial benign smooth muscle tumor.

Epidemiology

Age Can be seen in childhood. More common in adolescence or adulthood.

Gender M = F.

Prevalence Uncommon.

Etiology Usually acquired, except multiple piloleiomyomas.

Genetics Multiple piloleiomyomas are inherited in an autosomal dominant trait.

Skin Symptoms Chronic lesions can be sensitive to touch or cold; spontaneously painful.

Physical Examination

Skin Findings

Type Papules, nodules (Fig. 11-8).

Size 1 mm to 2 cm.

Color Flesh-colored to reddish-brown.

Palpation Firm, fixed to skin but freely movable over the underlying structures.

Shape Round.

Arrangement Grouped when multiple; tend to coalesce into plaques with arciform or linear configuration.

Distribution Extremities, trunk greater than the face, neck, vulva, penis, scrotum, nipple, and areola.

Genetics Mutation of the fumarate hydratase gene on chromosome 1q42.3–43.

General Findings

Leiomyomas typically have no associated systemic findings. Rarely, women with multiple inherited piloleiomyomas may have associated painful smooth muscle tumors of the uterus (familial leiomyomatosis cutis et uteri).

Differential Diagnosis

History, physical examination, and skin biopsy can help differentiate leiomyomas from angiolipomas, dermatofibromas, schwannomas, neurofibromas, glomus tumors, osteoma cutis, eccrine spiradenomas, neuromas, and neurilemmomas. Rarely, there can be leiomyosarcomas, which are typically larger than their benign counterparts.

Laboratory Examinations

Dermatopathology Pilar leiomyomas reveal a proliferation of haphazardly arranged smooth muscle fibers in the dermis, separated from the epidermis with a Grenz zone. Angioleiomyomas reveal a well-demarcated dermal nodule composed of concentrically arranged smooth muscle fibers around numerous slitlike vascular spaces.

Course and Prognosis

Leiomyomas are benign and are typically asymptomatic. Some lesions are painful. They have a high incidence of recurrence (50%) following removal but there are no reports of malignant transformation.

Management

Leiomyomas are benign and thus no treatment is necessary. For symptomatic lesions, possible treatments include surgical excision but the recurrence rate is high (50%). Other management options include topical nitroglycerine, systemic nifedipine, acetaminophen, lidocaine, or CO2 ablation with varied reported success.

A lipoma is a common benign tumor characterized by an asymptomatic, well-demarcated, soft nodule of mature fat cells. They are typically solitary lesions and benign, but can be multiple and associated with more diffuse disease (Table 11-2).

Epidemiology

Age Any age, most onset postpuberty.

Gender M > F.

Incidence Very common.

Etiology Familial multiple lipomatosis: AD inheritance. Increased in individuals with obesity, diabetes, or hypercholesterolemia. Some are posttraumatic. ? HMBA2 gene mutation with translocations on 12q13–15.

History

Lipomas are typically isolated asymptomatic nodules that are stable or slowly growing in size for years. Rates of growth seem to increase with weight gain and enlarging lesions may compress nerves and become painful. Multiple lipomas may be seen with associated disease (Table 11-2).

Physical Examination

Skin Findings

Type Single or multiple nodules.

Size Few mm to 10 cm.

Color Flesh-colored.

Shape Round, disc-shaped, or lobulated.

Palpation Soft, mobile.

Distribution Anywhere.

Sites of Predilection Neck, shoulders, trunk (Fig. 11-9), and buttocks.

Differential Diagnosis

The diagnosis of a lipoma is made by history and clinical examination. It can be confused with a cyst, or other subcutaneous masses.

Laboratory Examinations

Dermatopathology Encapsulated tumors composed of mature fat cells (large polygonal or spherical cells with lipid vacuole and peripherally displaced nucleus) intersected by thin strands of fibrous tissue.

Course and Prognosis

Most lipomas remain stable and asymptomatic. They may enlarge, impinge on nerve, and become tender. Malignant transformation (liposarcoma) is extremely rare and typically occurs in large lesions (>10 cm).

Management

Lipomas are usually benign and asymptomatic and thus no treatment is required. For symptomatic or enlarging lesions, surgical excision or liposuction can be performed.

A giant cell tumor of the tendon sheath is the most common tumor of the hand and presents with a firm enlarging nodule on the fingers.

Synonyms Localized nodular tenosynovitis, giant cell synovioma, pigmented villonodular synovitis.

Epidemiology

Age Any age, most onset between 30 and 50 years.

Gender F > M.

Incidence Very common.

History

Giant cell tumors are typically isolated asymptomatic nodules that are stable or slowly growing in size for years. Enlarging lesions may compress nerves and become painful or impair mobility.

Physical Examination

Skin Findings

Type Single nodule (Fig. 11-10).

Size Few millimeters to 1.5 cm.

Color Flesh-colored.

Shape Round.

Palpation Firm, immobile.

Distribution Finger > hand > toes.

Differential Diagnosis

The diagnosis of a giant cell tumor is made by history and clinical examination. It can be confused with a rheumatoid nodule, cyst, or subcutaneous granuloma annulare.

Laboratory Examinations

Dermatopathology Lobular growth attached to the tendon sheath with cellular areas of polygonal cells blending with hypocellular areas of spindle cells, with characteristic multinucleate giant cells scattered throughout.

Course and Prognosis

Giant cell tumors of the tendon sheath are benign, and may be reactive or neoplastic in nature.

Management

Giant cell tumors are benign and asymptomatic and thus no treatment is required. For symptomatic or enlarging lesions, surgical excision can be performed, but there is a 30% recurrence rate.