THE SPONTANEOUS appearance of a painful dusky discoloration threatening the viability of a single toe is especially puzzling to the physician when the pedal arterial pulsations are clearly palpable, the affected foot is otherwise arterially well nourished, and infection and trauma are absent. Diagnoses surrounding the catch-basket of "small vessel disease" such as gout, polycythemia, diabetes, collagen disorders, the vasospasms, and the allergic arteritides are incompatible with the abrupt onset and localized nature of the lesion. Spontaneous thrombosis of an "endartery" is an unsatisfactory explanation.
When, a few days or weeks later, a second toe remote from the first or a patch of skin over the foot or leg becomes equally suddenly ischemic or a palpable pedal pulsation disappears, minute-sized emboli are suggested. Since a cardiac source is rarely relevant, ulcerated atheromata with adherent red blood cell aggregates, lying between the renal arteries and the popliteal arterial trifurcation are suspect.