Proximal nailfold microhemorrhage events are manifested as distal cuticular (eponychial) hemosiderin-containing deposits (CEHD) (syn. Maricq sign) and can aid in the diagnosis of dermatomyositis and systemic sclerosis.

IMPORTANCE: Many patients present with cutaneous signs and symptoms that suggest a diagnosis on the autoimmune disease spectrum. During the "acute phase" of disease activity, patients with systemic sclerosis (SSc) and dermatomyositis (DM) have characteristic nailfold findings, including dilated capillaries, microhemorrhages, and hemosiderin deposits.

OBJECTIVE: To review the literature on the presentation of microhemorrhages and to highlight the differences (in terms of terminology, characterization, and clinical relevance) between proximal microhemorrhage events and the distal products, often thought of as "hemosiderin deposits" located in the cuticle (eponychium). Because we found no studies directly showing these cuticular products are in fact "hemosiderin-containing," we conducted a direct staining experiment in vivo using Prussian blue in order to increase our confidence that these products are indeed hemosiderin-containing and that the terminology is accurate for further use.

EVIDENCE REVIEW: In July-December 2014, the MeSH function in PubMed was used to identify approximately 165 articles relating to capillaroscopy. We reviewed these articles for mention of microhemorrhages and hemosiderin deposits. In addition, we used PubMed and Google Scholar searches for "hemosiderin + nail", "Prussian Blue + nail", and "hemosiderin deposit." We found no papers reporting the use of Prussian Blue directly on nailfolds of patients with SSc and DM in vivo.

FINDINGS: In our literature review, "microhemorrhages" and "hemosiderin deposits" were often used synonymously, yet they are clearly distinct entities. We present a case in which the presence of these deposits supported a diagnosis of amyopathic DM. We used Prussian blue staining solution to visualize the cuticular (eponychial) hemosoderin-containing deposits (CEHD) - distal cuticular products that reflect previous proximal nailfold microhemorrhage events. CEHD can serve as an indicator of active autoimmune disease, particularly in SSc and DM.

CONCLUSIONS AND RELEVANCE: CEHD are in fact hemosiderin-containing deposits that can reflect the active inflammatory phase of microvascular injury occuring in autoimmune disorders such as DM and SSc. CEHD can be visualized and documented at the bedside with tools commonly available to any dermatologist (portable dermatoscope and compact digital camera).