Novel ANKRD26 and PDGFRB gene mutations in pediatric case of non-Langerhans cell histiocytosis: Case report and literature review.

Cutaneous non-Langerhans cell histiocytosis (NLCH) is a rare and biologically benign entity that can be broadly classified into two categories: xanthogranuloma and non-xanthogranuloma. The xanthogranuloma family is characterized by a proliferation of histiocytes with both macrophage and dendritic cell differentiation, negative BRAF mutation, and rare Touton-type giant cells. Molecular studies have reported that mutations involved in the MAPK signaling pathways are implicated in the pathophysiology of histiocytoses. While LCH is associated with the somatic mutation of BRAF v600e, however, mutations and gene fusions in NLCH cases are undefined. We hereby present a 19-month-old female with recalcitrant nodular rashes diagnosed as NLCH with associated novel genetic mutation involving ANKRD26 and PDGFRB genes, as well as PDGFRB::CD74 fusion mRNA. Immunohistochemical staining showed strong and diffuse CD68 and CD163 positivity, and negative CD1a, CD207, ALK D5F3, S100 protein, and BRAF V600E (VE1). Albeit unknown significance, this case of an ANKRD26 and PDGFRB gene mutation in cutaneous NLCH has not been reported prior in the literature. Our case highlights the advantage of pathology and genetic studies in cutaneous NLCH to increase the understanding of this heterogeneous enigmatic disorder and identify further options in management.

Isotretinoin Associated Rhabdomyolysis: Monitoring Creatine Kinase and Educating Patients.

Monitoring specific values at baseline and throughout treatment is standard of care for isotretinoin therapy; however, creatine kinase (CK) blood monitoring is often excluded. Herein, we describe the importance of CK monitoring during isotretinoin therapy to assess the risk of rhabdomyolysis and potential renal damage, regardless of muscle-related symptom presentation. We present 2 patients with hyperCKemia: a 16-year-old male on isotretinoin whose CK levels were elevated (7,325 U/L) when rhabdomyolysis symptoms were present, and an asymptomatic 18-year-old male with elevated CK levels (35,000 U/L) before starting isotretinoin. Based on our experience, we strongly recommend obtaining CK levels to monitor for and potentially prevent rhabdomyolysis and its associated complications.

Verrucous venous malformation with thrombocytopenia in a neonate.

Verrucous venous malformations (VVM) are rare, congenital, slow-flow vascular anomalies that have been historically difficult to characterize due to clinical mimics and unclear histological evaluation. A life-threatening complication of VVMs is localized intravascular coagulation. Herein, we describe a male neonate who presented with a congenital VVM on the left lower extremity with associated severe thrombocytopenia. We discuss the multifaceted diagnostic approach used to identify this VVM, while highlighting the use of WT-1 as a negative predictive marker; we additionally outline novel treatment options and management beyond cutaneous involvement.