CONNECTIVE TISSUE NEVUS
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 systemic disease (Table 11-1).
| Syndrome | Inheritance | Cutaneous Findings | Associated Features |
|---|---|---|---|
|
Familial cutaneous collagenomas |
Autosomal dominant (possible LEMD3 gene mutation) |
Multiple collagenomas |
May have associated cardiomyopathy |
|
Tuberous sclerosis collagenomas |
Autosomal dominant (TSC1 or TSC2 gene mutation) |
Shagreen patch, adenoma sebaceum, ash leaf macules, café au lait spots, periungual fibromas |
Epilepsy, mental retardation, rhabdomyomas, calcified brain nodules |
|
Buschke–Ollendorff syndrome |
Autosomal dominant (LEMD3 gene mutation) |
Dermatofibrosis lenticularis disseminata |
Osteopoikilosis seen on x-ray, dysplasia of bone (leg bones, pelvis, hands, feet) |
|
Proteus syndrome |
Mosaic mutation (AKT gene mutation) |
Cerebriform connective tissue nevus, often on the feet (plantar collagenoma) |
Areas of sporadic, progressive overgrowth, vascular malformations, linear epidermal nevi, dysregulated adipose tissue |
SYNONYMS Nevus elasticus, juvenile elastoma, collagenoma, collagen hamartomas.
AGE Present at birth or childhood.
GENDER M = F.
PREVALENCE Uncommon.
GENETICS May have an autosomal dominant inherited form; see Table 11-1.
Connective tissue nevi are localized malformations of dermal collagen and/or elastic fibers.
Connective tissue nevi appear in childhood or adolescence and are asymptomatic but can be disfiguring.
TYPE Slightly raised plaque (Fig. 11-1). May have a pebbly surface.
COLOR Flesh-colored to yellow.
SIZE Few millimeters to several centimeters.
NUMBER Solitary or multiple.
DISTRIBUTION Symmetrically over abdomen, back, buttocks, arms, thighs. Occasionally linear configuration.
Can be associated with systemic disease (Table 11-1).
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.
DERMATOPATHOLOGY Skin biopsy reveals disorganized collagen and/or elastin fibers in the dermis. 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. Special staining for collagen or elastic fibers may aid in the diagnosis.
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 or other associated syndromes (Table 11-1).
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
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.
AGE Pigmentation onset 50% before 10 years, 25% between 10 and 15 years, and 25% after 15 years. Hypertrichosis may follow.
GENDER M > F, estimated 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, with lesions expressing heightened sensitivity to androgens.
Becker’s nevi are thought to have an increased number of androgen receptors accounting for their onset at/around puberty and the clinical appearance of smooth muscle thickening with hypertrichosis, hypertrophic sebaceous glands, and acne.
TYPE Isolated macule or plaque, smooth or verrucous surface, often with increased hair growth (Fig. 11-2).
COLOR Flesh-colored to tan to brown, blotchy.
SIZE One to several centimeters (average size approximately 125 cm2).
SHAPE Large, irregular shape.
NUMBER Typically solitary, may be multiple.
DISTRIBUTION Unilateral on shoulder or back; less commonly on extremities.
SIDE-LIGHTING Oblique lighting of the lesion will help to detect subtle elevation.
Associated findings are uncommon. In rare instances, underlying hypoplasia of the tissue may be present (i.e., shortened extremity, breast hypoplasia), termed Becker’s nevus syndrome.
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.
DERMATOPATHOLOGY Epidermal papillomatosis, acanthosis, hyperkeratosis, and occasional horn cysts. Hypertrichosis may be noted. 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.
Pigmentation occurs in adolescence usually followed by increased coarse hair growth in over half of affected males. Females with Becker’s nevi have less of a tendency to have hair growth in the lesion. After 2 years, the lesion tends to stabilize and may fade slightly but persists for life. Becker’s nevi 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 associated underlying anomalies: hypoplasia of the ipsilateral breast, arm, lumbar spina bifida, thoracic scoliosis, pectus carinatum, scrotal abnormalities, or enlargement of the ipsilateral foot.
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 rarely associated soft tissue or bony abnormalities.
RECURRENT INFANTILE DIGITAL FIBROMA
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.
AGE At birth or during the first years of life.
GENDER M = F.
ETIOLOGY Unknown.
Immunohistochemical and ultrastructural studies have shown that the fibroblasts contain myofilaments and demonstrate mitotic activity. Eosinophilic inclusions are suggestive of a possible viral etiology.
TYPE Nodules (Fig. 11-3).
SIZE Few millimeters to 3.5 cm.
COLOR Flesh-colored to pink.
NUMBER Most often solitary but can be multiple.
PALPATION Firm.
DISTRIBUTION Dorsolateral aspects of fingers or toes. Thumbs and great toes usually spared. Rarely on hands or feet without digital involvement.
History, physical examination, and skin biopsy can differentiate recurrent digital fibromas from verrucae, periungual fibromas, supernumerary digits, fibroepithelial polyps, or other dermal proliferations.
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) that are visible on routine hematoxylin/eosin stains and highlighted by trichrome staining.
The lesions of recurrent infantile digital fibromas appear in infancy and spontaneous involution may occur after several years.
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 up to 75% of cases, recurrences are observed in late childhood, at which time wide surgical excision may be required.
RUDIMENTARY SUPERNUMERARY DIGITS
Rudimentary supernumerary digits are soft tissue reduplicates that typically occur on the lateral sides of normal digits.
SYNONYM Rudimentary polydactyly.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
