Nodular Lesion in a Newborn with Spontaneous Regression

1. Xavier Sanchez-Flores, MD* 2. Oscar W. Nevares-Pomales, MD* 3. Rafael F. Martin-Garcia, MD* 1. *Department of Dermatology, University of Puerto Rico School of Medicine, San Juan, Puerto Rico A 4-week-old girl presents to the dermatology clinic with a nodular lesion over her right ala nasi that has been present since birth. She was born via spontaneous vaginal delivery at 39 weeks’ gestation as the first child to a healthy 29-year-old woman after an uncomplicated pregnancy and delivery. The mother reports no history of prenatal infection or complication. Neonatal growth parameters such as weight, length, and head circumference are within the normal ranges. Apgar scores were normal. Results of prenatal screening laboratory tests for group B streptococcus, hepatitis B, rubella antibodies, urinalysis, syphilis, complete blood cell count, and human immunodeficiency virus were reassuring. The family and social histories are noncontributory. The patient was born with a small, nonblanchable erythematous papule that rapidly grew to a yellowish-brown nodule with central crust (Fig 1). The lesion did not collapse on compression. There is no liver or spleen enlargement, fever, icterus, involvement of mucous membranes or superficial palpable lymphadenopathy. No other significant skin manifestations are observed. Results of diagnostic tests, including complete blood cell count, complete metabolic panel, coagulation profile, chest radiograph, whole-body scintigraphy, and newborn screening, are normal. The hematology-oncology service is consulted, but a bone marrow biopsy reveals no abnormalities or concerning findings. S-100 and CD1a stains are negative in the bone marrow sample. A skin biopsy reveals the diagnosis. Figure 1. Erythematous, ulcerated nodule with mild crusting. The skin biopsy demonstrates an ulcerated epidermis with a diffuse and lichenoid mixed dermal infiltrate mostly composed of large cells with kidney-shaped reniform nuclei along with scattered lymphocytes and few eosinophils. Immunohistochemical staining with CD1a and S-100 shows strong reactivity in …