Converging Neoplasms and the Environmental Exposome: Four Distinct Encounters with Collision Tumors in Dermatology

Collision tumors - characterized by two or more distinct cell types within a singular lesion - are uncommon yet intriguing dermatological phenomena, presenting diagnostic and therapeutic enigmas. Our case series details four diverse presentations of such tumor intersections in dermatology. Beyond the individual cases, we embark on an exploration into the potential environmental exposome's role in the emergence of these neoplastic overlaps. While the first and fourth cases underscore serendipitous discoveries during an excisional biopsy, the second revolves around diagnostic ambiguity arising from concurrent neoplasms. The third case delineates the challenges in surgical management due to intertwined tumor entities. Integral to our investigation, histopathological evaluations helped demarcate the distinct tumor types. We then delve into environmental factors - cumulative ultraviolet radiation, air pollutants, chemical carcinogens, and smoking - speculating their role in tandem neoplastic presentations. Cutaneous collision tumors are infrequently occurring neoplasms of unknown origin characterized by two or more distinct cell types within a singular lesion. This series highlights a potential connection between specific environmental exposome and the development of collision neoplasms. An appreciation of this potential relationship will hopefully incite interdisciplinary collaborations and holistic management strategies, improving patient outcomes in the face of these dermatological rarities.