“…In the first, obstruction of lymphatic vessels and congestion of lymphatic fluid caused by the growth of the tumor nodule causes dilatation of lymphatic vessels, leakage of lymphatic fluid, and edema in the dermis surrounding the tumor, which further produces the bullous appearance. 2,5 The second theory suggests that the presence of matrix metalloproteinases (MMP-9 and MMP-12), released by fibroblasts and inflammatory cells surrounding the tumor, may be associated with the degradation of elastic fibers and collagen, resulting in the bullouslike/anetodermic appearance. 6 Histologically, bullous pilomatricoma not only has the hallmarks of pilomatricoma, including basaloid cells and eosinophilic keratinized (shadow) cells, but also shows dilated lymphatic vessels, giant cell reaction, lymphoedema, disruption of collagen fibers, dilated blood vessels, fibrous capsule, calcification, nests of transitional cells, and necrosis.…”