The diagnosis of acrocyanosis is clinical based on persistence and typical localization of the skin color changes. It requires exclusion of other conditions characterized by blue skin color changes. The diagnosis of primary acrocyanosis should be entertained only after causes of secondary acrocyanosis have been excluded.
Primary acrocyanosis is a chronic, benign condition without tendency to progress, pain, or tissue loss. Skin changes tend to be painless and persistent and may be more pronounced in cold ambient temperatures and with dependency; skin color normalizes with elevation of the extremities (Figure 76-2A-D). Hyperhidrosis and clamminess of the hands and feet are often seen which worsens in warm temperature while skin color improves. Mild localized edema may be present.4
Foot of a man with acrocyanosis photographed in supine (A) and dependent (B) positions. Hands of the same patient in supine (C) and (D) dependent positions.
Crocq sign is classical, although nonspecific, and denotes slow and irregular return of the blood from the periphery (rather than from beneath) to the center of a blanched skin area created by local pressure (Figure 76-3A).
(A) A 34-year-old woman with moderate positivity of immunoglobulin G (IgG) anti-beta-2 glycoprotein-1 antibodies. Purplish skin discoloration is noted in the dependent position. It improves with lifting of her feet above the head level. There are no skin changes above the ankles or in upper extremities. The blue discoloration can be pressed away, but quickly refills. (B) For comparison, feet of the patient's mother are photographed next to the patient's. (Photograph courtesy of Dr. Stephan Moll, University of North Carolina, Chapel Hill, NC.)
Cyanotic skin changes in the distal (acral) parts of the body are seen, typically in hands and feet (Figures 76-1,76-2,76-3, and 76-4); however, nose and ears may be involved. Skin changes are diffuse and symmetric in primary acrocyanosis and are almost never proximal to the level of ankle or wrist with normal-appearing skin above that line (Figures 76-3B and 76-4).4
A man in his 50s with a psychiatric history and significant malnourishment. He had a negative medical workup, including search for an occult malignancy. (Photograph courtesy of Dr. Steven M. Dean, Ohio State University, Columbus, OH.)
There are no specific laboratory tests for acrocyanosis. Hyposphygmia on plethysmography and decreased oxygen tensions with transcutaneous oximetry may be observed. Local skin temperature is low; blood flow is decreased. Various methods of capillaroscopy have been evaluated. Hemorrhages, pericapillary edema, and widened and rarified capillaries are often observed with commonly described "megacapillaries." However, there is no consensus on capillaroscopic criteria, and the method is not clinically reliable. In secondary acrocyanosis, the workup may be extensive but is focused on identifying one of the many specific causes.1