Giant Congenital Sclerosing Blue Nevus of the Scalp Presenting with Rapidly Disseminated Fatal Metastases in a Pediatric Patient.

1 Michael V. DeFazio, MD Jerry W. Chao, MD Albert K. Oh, MD Gary F. Rogers, MD Division of Plastic and Reconstructive Surgery Children’s National Medical Center Wash. Sir: G congenital blue nevi (GCBN) are rare dermal melanocytic proliferations that are distinguished by their large size, aggressive behavior, and propensity for malignant degeneration.1 To date, only 18 cases of GCBN involving the scalp have been reported. Among these, local invasion into the calvaria/dura (n = 10), malignant transformation (n = 6), and disseminated metastases (n = 5) were observed.2 Although the precise nature of malignant change is unclear, adults with histopathologically cellular GCBN are most commonly affected.2 We report the first case of a sclerosing GCBN of the scalp presenting with rapidly progressive fatal metastases in a toddler. A 17-month-old girl presented for evaluation of a 15 × 20-cm blue-gray plaque of the scalp that had grown commensurately with the child since birth. The patient’s history was notable for posterior encephalocele repair during infancy, resulting in an occipital bone defect and chronic/stable ulceration at the vertex. Initial magnetic resonance imaging demonstrated a noninvasive parietooccipital mass with an underlying 12-cm2 calvarial defect. Multiple incisional biopsies from ulcerated and nonulcerated regions revealed histopathologic features of sclerosing GCBN with extensive dermal/subcutaneous infiltration (ie, spindle-shaped melanocytes/dense collagenous stroma). Given these benign findings, conservative observation/local wound care was pursued in the hopes that dural-induced calvarial regeneration would improve the safety of tumor resection from the underlying scarred dura. However, the patient presented 7 months later with rapidly enlarging subcutaneous nodules, necrosis, and new-onset pain, vomiting, and ataxia (Fig. 1). Repeated magnetic resonance imaging demonstrated interval development of 2 sublesional masses with intracranial extension and calvarial/dural invasion (Fig. 2). A histopathologic diagnosis of melanoma (ie, atypical epithelioid melanocytes, large/pleomorphic nuclei, necrosis, numerous mitoses) arising within the areas reminiscent of sclerotic blue nevus was confirmed. Immunostains for BRAF V600 were negative; however, homozygous deletion of the 9p21 locus (CDKN2A/P16 tumor suppressor) was identified in 40% of cells analyzed by fluorescent in situ hybridization. Total body positron emission tomography revealed disseminated visceral metastases. The patient subsequently died 3 weeks later from widespread metastatic disease. This case presents several unique findings that deviate from previously reported trends. Morphologically, the majority of GCBN display cellular histopathologic features, which correlate well with their proclivity for invasive growth and malignant degeneration.1,2 In contrast, sclerosing blue nevi are predominantly benign, solitary, well-circumscribed nodules. Focal malignant melanoma arising within this subtype has been reported only once; however,