Dermoscopy of chilblain-like lesions during the COVID-19 outbreak: A multicenter study on 10 patients.

To the Editor: We recently reported 63 patients who developed chilblain-like lesions (CBL) during the COVID-19 pandemic, but the association with severe acute respiratory syndrome coronavirus 2 has not been proven. Because most patients' information was not previously obtained by in-person visits by the investigators, dermoscopy was not available.

Ten patients with CBL were recruited from April 1 to 15, 2020 (Table I ). There were 7 male and 3 female patients, with a median age of 13 years (range, 11-20 y). The feet were mostly affected (8/10 patients). The erythematous-edematous type was seen in 8 of 10 patients, and the blistering type was observed in 2 of 10 patients. The median time to diagnosis was 13 days (range, 6-34 d). Patients were otherwise healthy, and COVID-19 status, when investigated through swab (1/10) or serology (2/10), was negative.

Table I

Patients' characteristics

Patient	Sex	Age, y	Location	Time to diagnosis, d	Clinical type	Dermoscopy
						Background	Vessels	Other findings
1	M	20	Feet	14	Erythematous-edematous	Erythematous	Dotted	—
2	M	11	Feet	33	Erythematous-edematous	Erythematous	Linear	—
3	M	13	Feet	34	Blistering	Coppery red	Hemorrhagic dots, linear	—
4	F	12	Feet	10	Erythematous-edematous	Coppery red	Hemorrhagic dots	—
5	M	14	Feet	10	Erythematous-edematous	Coppery red	Hemorrhagic dots	CrustsPurple unstructured areasBullae
6	M	13	Feet	12	Blistering	Coppery red	Hemorrhagic dotsGlomerular Vessels	CrustsPurple unstructured areas
7	F	11	Hands/feet	10	Erythematous-edematous	Coppery red	Irregular linear vesselsCuticular vesselsVessels with branches	Multiple short vessels arranged perpendicularlyPurple unstructured areas
8	F	13	Hands	15	Erythematous-edematous	Erythematous	Hemorrhagic dotsIrregular dotsCuticular vessels	—
9	M	12	Feet	6	Erythematous-edematous	Coppery red	Hemorrhagic dotsDotted, irregular linear vessels	Round brown unstructured area with within halo
10	M	13	Feet	17	Erythematous-edematous	Erythematous	Dotted	—

F, Female; M, male.

Dermoscopy evaluated background color, vessels, and additional features. Background color was coppery red in 6 of 10 and red in 4 of 10 patients. Erythema was blanching in early cases, and it did not disappear in long-standing red-purple lesions. In plantar lesions, erythema mostly involved ridges. Vessels were seen in all patients. Hemorrhagic dots were commonly detectable (6/10); nonblanching blurred dotted, linear, glomerular, and irregular vessels were occasionally found. Additional features, including crusts and whitish areas, were seen in the blistering type (Figs 1 and 2 ).

Fig 1

A, Dermoscopy findings of a classical erythematous-edematous lesion of the dorsal aspect of the toe showing a predominant coppery red background associated with dotted vessels and hemorrhagic dots. B, Dermoscopy of a blistering-type CBL showing a coppery red background associated with hemorrhagic dots and crusts. C, Another dermoscopic facet of a blistering lesion of the toe showing a white area corresponding to skin detachment. Note how the erythema is mainly distributed on the ridges. CBL, Chilblain-like lesions.

Fig 2

A, A plantar lesion at dermoscopy showing a coppery red background associated with nonblanching hemorrhagic dots. B, Another lesion of the sole with erythema on the background, mostly seen on plantar creases. C, The late phase of CBL, showing on dermoscopy coppery red areas and blurred dotted vessels. CBL, Chilblain-like lesions.

Because there was an outbreak of CBL, it was quite logical to think about a causal relationship between COVID-19 and CBL, although poor data about patients' COVID status did not allow us to confirm this supposition. , Most patients were adolescents, and only a minority presented mild systemic symptoms preceding cutaneous signs. A possible mechanism could be a delayed immune reaction to the viral infection leading to microvascular damage and secondary development of cutaneous lesions. Dermoscopy could be a support in discovering the morphologic features of CBL and the potential pathogenesis hiding behind this mysterious sign.

In most patients, a coppery red background was present at dermoscopy, probably indicating the presence of inflammatory cells and hemosiderin in the dermis. The presence of vascular damage was also indicated by hemorrhagic dots and nonblanching vessels. The presence of some additional features in the blistering type confirms that there was skin detachment in those patients. These dermoscopic findings could be partially justified by the histologic features recently described, with dermal and perivascular lymphocyte infiltrate associated with keratinocyte necrosis. Dermoscopic findings of CBL are not novel, because they overlap with those of pigmented purpuric dermatoses (PPD) and chilblains. The combination of coppery-red background with hemorrhagic dots is typical of the PPD, whose association with viral infections has been sometimes documented. On the other hand, the similarity of CBL to chilblains is not only clinical but also dermoscopic, so we maintain that the denomination of CBL for this cutaneous sign could be the most appropriate and that the term acro-ischemia should be avoided. The dermoscopic analogy with PPD could suggest a common histopathology, with a perivascular lymphocyte infiltration and augmented erythrocyte extravasation, although different reasons could lie at the bases of the 2 different conditions.

Our preliminary dermoscopic observations suggest a possible pathogenic explanation for this poorly understood condition.