Atypical and malignant cutaneous tumors are understudied in the pediatric population, with limited data on long-term follow-up. This study examines pediatric (0–18 years) atypical melanocytic proliferations over a twenty-year period (January 2002–December2022) using the EPIC SlicerDicer at our institution. Over a twenty-year period, there were 55 cases of pediatric melanoma (53 patients). The median follow-up time was 8 years, 11 months. A proportion of 96% were treated with wide local excision (WLE), and 47% had a sentinel lymph node biopsy (SLNB) (35% positive rate). There were 101 atypical Spitz tumor cases (85% atypical Spitz tumors, 15% Spitz melanoma), with a median follow-up duration of 9 years. A proportion of 77% were treated with WLE (with one patient dying of metastatic disease). There were 10 cases of atypical melanocytic proliferations not otherwise specified, including 5 pigmented epithelioid melanocytomas (PEM), 4 deep-penetrating nevi, and 1 atypical cellular blue nevus. This study adds to the growing body of knowledge on pediatric atypical cutaneous melanocytic proliferations, aligning with many described characteristics such as disease location and overall survival rates, with distinct exceptions (higher melanoma positive SLNB rate, lower atypical Spitz tumor WLE rate, and a case of fatal metastatic atypical Spitz tumor).

Introduction: Diagnostic uncertainty for ambiguous lesions that fall on the spectrum between nevi and melanoma remains a significant challenge and can have consequences for patient management. Methods: This study aimed to compare the diagnostic utility of preferentially expressed antigen in melanoma (PRAME) immunohistochemistry to molecular testing (FISH and SNP array) in 34 diagnostically challenging melanocytic lesions and 9 non-diagnostically challenging melanomas. Results: We conclude that while PRAME immunohistochemistry demonstrates high specificity (96.2%) in diagnostically challenging melanocytic lesions, its low sensitivity (12.5%) suggests that it should not replace histopathological evaluation in rendering the final diagnosis. Conclusions: These findings suggest that PRAME may serve as a useful adjunct in the diagnostic workup, particularly due to its high negative predictive value, but should be used in conjunction with other established diagnostic modalities.

Microporous annealed particle (MAP) scaffolds are injectable granular materials comprised of micron sized hydrogel particles (microgels). The diameter of these microgels directly determines the size of the interconnected void space between particles where infiltrating or encapsulated cells reside. This tunable porosity allows us to use MAP scaffolds to study the impact of spatial confinement (SC) on both cellular behaviors and the host response to biomaterials. Despite previous studies showing that pore size and SC influence cellular phenotypes, including mitigating the macrophage inflammatory response, there is still a gap in knowledge regarding how SC within a biomaterial modulates immune cell recruitment in vivo in wounds and implants. Thus, we studied the immune cell profile within confined and unconfined biomaterials using small (40 μm), medium (70 μm), and large (130 μm) diameter spherical microgels, respectively. We discovered that MAP scaffolds imparted regenerative wound healing with an IgG1-biased Th2 response. MAP scaffolds generated from 130 μm diameter microgels have a median pore size that can accommodate ∼40 µm diameter spheres induced a more balanced pro-regenerative macrophage response and better wound healing outcomes with more mature collagen regeneration and reduced levels of inflammation.