A 32-year-old white woman with a history of multiple endocrine neoplasia type 1 presents with multiple oval hypopigmented papules on her trunk and limbs. She notes that the papules initially appeared around puberty and have increased in number and size gradually. Dermatologic examination reveals multiple oval to round hypopigmented papules measuring 5 to 15 mm on her abdomen, chest, and back.
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Collagenomas are a type of connective tissue nevi characterized by excess collagen in the deep layers of the dermis. Collagenomas are skin-colored or hypopigmented oval to round papules ranging in size from 5 to 15 mm.1 The lesions may be solitary or multiple and occasionally occur in a linear arrangement. They are often clinically subtle and may be difficult to discern from normal skin.
Collagenomas may be inherited or acquired, and differentiation is determined based on time of onset, region affected, and family history. Inherited collagenomas include familial cutaneous collagenomas and shagreen patches of tuberous sclerosis. Familial cutaneous collagenomas usually affect the trunk, back, and upper arms and appear during the second or third decade of life. Conversely, acquired collagenomas such as eruptive collagenomas are seen on the head, neck, and lower limbs, and they may occur at any age.2
Collagenomas are more common in patients with multiple endocrine neoplasia type 1 (MEN1), an autosomal-dominant disorder resulting in tumors of the parathyroid, pancreas, and other endocrine organs.3 MEN1 is characterized by the combination of endocrine symptoms and possible cutaneous lesions. The cutaneous lesions of MEN1 include multiple facial angiofibromas, collagenomas, and café au lait macules (reported in 88%, 72%, and 38% of patients, respectively).4 These cutaneous lesions can aid in the diagnosis of MEN1 before the onset of endocrine symptoms.
Shagreen patches are a type of collagenoma seen in patients with tuberous sclerosis. Tuberous sclerosis is a rare autosomal-dominant multisystem genetic disease that results in seizures, intellectual disability, and skin findings. The cutaneous manifestations of tuberous sclerosis include collagenomas, facial angiofibromas, ash leaf macules, and periungual fibromas. Patients with tuberous sclerosis can also have ocular hamartomas as well as hamartomas of internal organs such as the heart, kidneys, brain, and lungs. The shagreen patches of tuberous sclerosis are typically found on the lower back and are usually flesh-colored or hyperpigmented, and in rare cases, they may be hypopigmented. They have an uneven, pebbly surface and may grow to approximately 10 cm in diameter. Shagreen patches usually begin to develop when the person is aged 2 years and eventually affect approximately half of all patients with tuberous sclerosis.5
The differential diagnosis for a collagenoma includes an elastic nevus, nevus anelasticus, and papular elastorrhexis, scar, anetoderma, and fibrous hamartoma of infancy.2
Histologically, collagenomas are defined by a poorly demarcated area of excess collagen fibers without an increase in fibroblasts. Diminished elastin fibers in the dermis of the skin may also be found. Connective tissue alterations of collagenoma may be more readily visible when compared with adjacent normal skin. Stains such as the Verhoeff-Van Gieson stain may also be useful to distinguish collagenoma histologically.5
Collagenomas are benign, thus no active treatment is required. However, collagenomas are rarely seen without accompanying secondary conditions; therefore, treatment of a secondary condition, such as MEN1 or tuberous sclerosis, may be required. Treatment of a collagenoma in the setting of MEN1 would likely include the removal of tumors of the neuroendocrine areas.4
- Park MY, Choi YJ, Lee JY, Shin MS, Ahn JY. A case of familial cutaneous collagenoma. Ann Dermatol. 2011;23 Suppl 1: S119-S122.
- Sharma R, Verma P, Singal A, Sharma S. Eruptive collagenoma. Indian J Dermatol Venereol Leprol. 2013;79(2):256-258.
- Darling TN, Skarulis MC, Steinberg SM, Marx SJ, Spiegel AM, Turner M. Multiple facial angiofibromas and collagenomas in patients with multiple endocrine neoplasia type 1. Arch Dermatol. 1997;133(7):853-857.
- Furtado S, Ghosal N, Furtado SV, Gupta K, Hegde AS. Neurocutaneous spectrum of multiple endocrine neoplasia-1. Indian J Dermatol Venereol Leprol. 2012;78(1):93-96.
- Bolognia JL, Jorizzo JL, Schaffer JV, eds. Dermatology. 3rd ed. Philadelphia, PA: Elsevier Saunders; 2012.