A 32-year-old woman, gravida 2 para 1, at 28 weeks gestation comes to the office for a routine prenatal visit. Three weeks ago, she developed a facial rash that has darkened despite the use of lotions. For the past week, the patient has been unable to work at her job at a landscape company due to increasing fatigue and dizziness on standing. She has had no contractions, vaginal bleeding, or leakage of fluid. Fetal movement is normal. The patient has no chronic medical conditions and takes a daily prenatal vitamin and iron supplement. Temperature is 36.7 C (98.1 F), blood pressure is 110/70 mm Hg, and pulse is 72/min. Fetal heart rate is 145/min. Light brown, irregularly shaped macules are arranged in a bilaterally symmetric fashion on the patient's cheeks and nasal bridge. The macules do not affect the nasolabial fold. Laboratory results are as follows: Which of the following is the best next step in evaluation of this patient?

Question

A 32-year-old woman, gravida 2 para 1, at 28 weeks gestation comes to the office for a routine prenatal visit.  Three weeks ago, she developed a facial rash that has darkened despite the use of lotions.  For the past week, the patient has been unable to work at her job at a landscape company due to increasing fatigue and dizziness on standing.  She has had no contractions, vaginal bleeding, or leakage of fluid.  Fetal movement is normal.  The patient has no chronic medical conditions and takes a daily prenatal vitamin and iron supplement.  Temperature is 36.7 C (98.1 F), blood pressure is 110/70 mm Hg, and pulse is 72/min.  Fetal heart rate is 145/min.  Light brown, irregularly shaped macules are arranged in a bilaterally symmetric fashion on the patient's cheeks and nasal bridge.  The macules do not affect the nasolabial fold.  Laboratory results are as follows:  Which of the following is the best next step in evaluation of this patient?

Quizplus · Accepted Answer

11ec25c8_d29f_3a9a_bc81_758bd67b9c0b_MD0003_00 This patient has melasma, an acquired hyperpigmentation disorder that occurs primarily on sun-exposed areas of the face. Melasma likely occurs when ultraviolet radiation triggers melanocyte proliferation and pigment deposition in sun-exposed areas. It is more common in women of reproductive age, particularly during pregnancy, as estrogen and progesterone also stimulate melanocyte proliferation. Additional risk factors include darker skin color, thyroid dysfunction, medications (eg, antiepileptics), and cosmetic use. Patients typically develop irregularly shaped, hyperpigmented macules of varying color (eg, light to dark brown, ash/blue) that occur in a symmetric centrofacial, mandibular, or malar distribution (as in this patient). Melasma is diagnosed clinically and therefore requires no further evaluation. Management during pregnancy includes minimizing progression of the hyperpigmentation with sun avoidance and broad-spectrum sunscreen use. Melasma typically resolves postpartum; areas that do not resolve can be treated with skin-lightening agents or topical retinoids. (Choice A) Patients with insulin resistance (eg, gestational diabetes mellitus) can develop acanthosis nigricans, which appears as hyperpigmented, velvety plaques in intertriginous areas (eg, neck, axillae) rather than the face. However, a 3-hour glucose tolerance test is not indicated in this patient as her 1-hour glucose challenge test is normal (<140 mg/dL). acanthosis nigricans (Choice B) Systemic lupus erythematosus can present with a malar rash that spares the nasolabial folds; however, the rash typically is erythematous and scaly appearing. Additional clinical features may include hypertension, anemia, thrombocytopenia, and proteinuria. Antinuclear antibody testing is not indicated in this patient, as increasing fatigue and dizziness on standing are common in the third trimester due to physiologic changes of pregnancy. (Choice D) A serum cortisol level is used in the evaluation of adrenal insufficiency, which can present with hyperpigmentation and fatigue; however, the hyperpigmentation is typically generalized rather than focal. (Choice E) Serum iron studies are used to evaluate for hereditary hemochromatosis. Patients can develop skin hyperpigmentation or bronze discoloration; however, it is not limited to the face, as in this patient. Educational objective: Melasma, an acquired hyperpigmentation disorder that commonly occurs during pregnancy, typically presents with bilateral, symmetric macules on sun-exposed areas of the face. Melasma is clinically diagnosed and typically resolves postpartum. It is managed with avoidance of sun exposure and broad-spectrum sunscreen use. References: Melasma: a clinical and epidemiological review. (http://www.ncbi.nlm.nih.gov/pubmed/25184917) Physiologic changes of pregnancy: a review of the literature. (http://www.ncbi.nlm.nih.gov/pubmed/29234716) Pigmentation and pregnancy: knowing what is normal. (http://www.ncbi.nlm.nih.gov/pubmed/27926637)

A 32-Year-Old Woman, Gravida 2 Para 1, at 28 Weeks