Periumbilical Acanthosis Nigricans along the Surgical Site of Umbilical Hernia Operation

Sir,

Acanthosis nigricans (AN) is characterized by symmetric, brown-black velvety plaques that are especially seen in the axillae, neck, groin, inframammary folds, popliteal fossae, elbows, and umbilical region. It is much more common in dark-skinned individuals. AN is classified into eight subtypes: benign, obesity-related, syndromic, malignant, acral, unilateral (nevoid), secondary to medication, and multifactorial. The more common type is obesity-related AN associated with insulin resistance (IR) that may be associated with type 2 diabetes mellitus (DM), metabolic syndrome, and polycystic ovary syndrome.[1] IR is the key factor in AN. This association is explained by the fact that hyperinsulinemia activates insulin-like growth factor-1 (IGF-1) receptors located in fibroblasts and keratinocytes, stimulating their proliferation.[2]

A 57-year-old female patient presented with a dark brown-black discoloration on the umbilicus and periumbilical region that was present for 4 years after the umbilical hernia operation. Her body mass index was 39.9. She had central obesity, type-2 DM, hypertension, and hyperlipidemia. She was in menopause for 9 years. She was using ramipril-hydrochlorothiazide as antihypertensive. Dermatological examination revealed a dark brown velvety plaque and black papules on the umbilicus and periumbilical region just over the previous surgical scar [Figure 1]. Rest of the skin including the skin folds and mucous membranes were normal. Routine hematological and biochemical tests were normal. Gynecological examination was normal except for an endometrial polyp that was detected by endocervical curettage. Chest radiography, abdomen ultrasonography, and abdomen magnetic resonance imaging were normal. Ultrasonography of breasts was consistent with Breast Imaging-Reporting and Data System (BI-RADS 1). Histopathological examination of a punch biopsy from the lesion showed lamellar hyperkeratosis, papillomatosis, basal hyperpigmentation in the epidermis, perivascular edema, and chronic inflammatory cell infiltration in the dermis [Figure 2]. Based upon the clinical and histopathological findings, the patient was diagnosed as AN. Topical treatment with tretinoin 0.01% cream was started.

Figure 1.

Dark brown macules and plaque and black papules on and around the umbilicus along the operation scar line

Figure 2.

Lamellar hyperkeratosis, papillomatosis, basal hyperpigmentation in the epidermis, perivascular edema, and chronic inflammatory cell infiltration in the dermis (H and E × 40)

Unilateral nevoid AN is a rare form of AN that is not associated with syndromes, endocrinopathies, drugs, or malignancies. Although various cases involving the face, scalp, chest, and inframammary region exist, only three cases with periumbilical localization have been reported to date. In contrast to the term “unilateral,” all of them have occurred on the middle of the abdomen including the umbilicus with a bilateral and symmetrical distribution.[3,4] Similarly, our case showed a bilateral distribution around the umbilicus and no other involvement was observed. It was interesting in our case that the lesion had developed just over the surgical site after the umbilical hernia operation. This may be due to the increased IGF-1 and IGF-2 in the wound healing process. It is known that IGF-1 and IGF-2 are differentiation factors that facilitate wound healing by stimulating fibroblast proliferation and enhancing collagen synthesis and the cutaneous changes seen in AN are the result of growth factor stimulation of keratinocytes and dermal fibroblasts.[5] Our case was obese and she had type 2 DM; these factors might have facilitated the development of AN. To our knowledge, this is the first case of AN with isolated umbilical localization over a surgical scar.

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Conflicts of interest

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