Review of diseases occurring together with LV and of laboratory findings encountered in LV demonstrates that no single disease, cause, or mechanism could be identified so far to be responsible for LV. This supports our interpretation that LV is not a specific disease, but a distinctive clinicopathologic pattern that may occur in a variety of different circumstances, chief among them being alterations of the coagulation cascade of various causes. The unifying features of this pattern are the presence of thrombi in the lumina of vessels of the dermis together with a perivascular infiltrate of inflammatory cells. Lesions clinical vary according to the position in the dermis of the vessels affected. Neither clinical nor histopathologic findings allow determination of the underlying cause in detail. A patient with LV needs to be worked up completely in regard to alterations of coagulation, malignancies, and rheumatologic disorders. Conceiving of LV as a pattern and not as a single disease explains also why no single treatment has been identified that cures LV consistently.