In summary, compared with paraneoplastic hypercalcemia of solid and hematological tumors, paraneoplastic hypercalcemia in NEN shares PTHrP as the most common causal agent with solid tumors, while paraneoplastic hypercalcemia in lymphomas is more frequently caused by 1,25(OH) vitamin D. Furthermore, paraneoplastic hypercalcemia in NEN seems to be less severe than in solid and hematological tumors. Here, PTHLH is linked to hypercalcemia disease.