SARS-CoV-2-related chilblains

We thank C. Dewar for her interest in our publication. We first iterate that a broad workup for contributory and aggravating causes was considered and a complete assessment was conducted during the clinical encounter. However, this could not all be captured within the article’s word limit. For clarification, we provide further details.

During the early months of the COVID-19 pandemic, our patient was assessed in-person in the emergency room, enabling a thorough history and a complete physical examination. Our patient had no history of nicotine or psychostimulant consumption. In addition, her review of systems was negative, including for those of autoimmune disorders and malignancy (i.e. no fevers, night sweats, weight changes, oral/genital ulcerations, photosensitivity, arthritis, arthralgias, morning stiffness, myalgias, muscle weakness, sicca symptoms, or other cutaneous eruptions). The patient also did not have a family history of known autoimmune conditions. Other than the acral lesions described in our article, her physical examination was unremarkable. In particular, she had a normal body habitus without clinical signs of anorexia nervosa, no other cutaneous findings such as oral ulcerations or photo-distributed lesions, and, normal nail capillaroscopy. Muscoskeletal examination was not pursued given lack of symptoms.

A thorough panel of investigations was completed to rule out systemic causes of chilblains. Imaging investigations were not conducted given the absence of respiratory symptoms before, during and after clinical encounter, and because chest imaging is not recommended to diagnose COVID-19 in patients with mild features (1). In addition, imaging would not have altered the cutaneous management.

We agree that a skin biopsy is not always required for diagnosis of chilblains as the findings are not pathognomonic but rather supportive of a clinical diagnosis. Our patient presented early during the pandemic when little was known about SARS-CoV-2-related chilblains. For SARS-CoV-2-related chilblains, there have been reports of classic chilblains histology, as well as superficial and deep lichenoid lymphocytic changes with basal vacuolar changes (2,3); microthrombi have also been described (4,5). A biopsy was completed to assess for microthrombi and rule out vaso-occlusive pathology.

Idiopathic chilblains remains a diagnosis of exclusion. Patients presenting with chilblains should thus be appropriately examined and investigated to rule out secondary systemic causes. Our patient’s thorough history, physical examination and subsequent work-up did not support any underlying disorder. SARS-CoV-2-related chilblains was favoured due to negative secondary work-up, absence of cool/damp exposure and positive serology. The understanding of SARS-CoV-2-related chilblains and its pathogenesis will continue to evolve in the coming months.