Background: Both targetoid hemosiderotic hemangiomas (THH) and solitary angiokeratomas (SAK) are acquired vascular malformations formed by superficial vascular ectasias possibly caused by trauma. Objective: We compare the clinicopathologic findings of THHs with those of SAKs and report the clinicopathologic findings of 3 singular cases of THH affected by cyclic or episodic morphologic changes. Methods: We performed a clinicopathologic study on 33 cases of THH and compared this group with 20 cases of SAK. On selected cases, histochemical and immunohistochemical analyses were evaluated. Results: Overlap of all the clinical and pathologic features studied were identified for THH and SAK. Clinically, they both commonly exhibited a brown or black papule located over the lower extremities that mimicked a melanocytic lesion. Histologically, they both had ectatic papillary dermal vessels with overlying epidermal hyperplasia, and adjacent hemosiderin deposits, extravasated red blood cells, lymphocytic infiltrate, and lymphangiectases. Compared with SAKs, THHs were significantly larger (5.3 vs 3.2 mm), more often excised (elliptical excision) than shave or punch biopsied, and had deeper dermal vessel alterations, more frequent dissecting vascular spaces, and more extensive hemosiderin deposits (all P < .01). THHs presenting with episodic changes were significantly larger than those without (11 vs 4.4 mm, P = .001). Conclusion: THHs and SAKs differ in degree, not in type, of clinicopathologic characteristics. This finding suggests that THHs are larger variants of SAKs whose size is the cause of more extensive, prolonged, or recurrent vessel damage. The histologic findings of extravasated red blood cells, hemosiderin, telangiectases, lymphangiectases, and fibrosis implicate trauma in the cause of these acquired vascular malformations. (J Am Acad Dermatol 1999;41:215-24.)