Sir,

We report a case of symmetrical drug-related intertriginous and flexural exanthema (SDRIFE)-like rash suspected to be associated with COVID-19 infection.

A 58-year-old woman with bipolar disorder presented with sore throat, fever, and cough. A nasopharyngeal swab PCR test result was positive for COVID-19, for which the patient began to take acetaminophen, L-carbocysteine, eprazinone hydrochloride, tranexamic acid, and dequalinium chloride. The next day, an itchy rash appeared on her left flank. She visited several clinics, but the rash gradually spread. She was admitted to our hospital 7 days after the onset of COVID-19.

At presentation, her respiratory status was stable. Physical examination showed mildly pruritic erythema symmetrically extended over her axillae, cubital fossae, flanks, lower abdomen, groin, buttocks, and thighs (Fig. 1a). Some serous blisters on the flanks, groin, and thighs had erythematous base (Fig. 1b). Significant laboratory findings were as follows: white blood cell count, 3700/ml; lymphocyte count, 1036/ml; and C-reactive protein, 3.98 mg/dL. Chest X-ray and CT images showed no evidence of pneumonia. A skin biopsy of the serous blisters on the front of the thigh revealed pronounced edema just below the epidermis and inflammatory infiltrates with eosinophils (Figs. 2a and 2b). Drug transformation test was negative for acetaminophen, L-carbocysteine, eprazinone hydrochloride, and tranexamic acid. The treatments given were antihistamines and topical steroids. The rash progressively disappeared over the following six days.

	Figure 1: a) Symmetrical gluteal and intertriginous erythema. b) Some serous blisters on the flanks, groin, and thighs had an erythematous base.
	Figure 2: A skin biopsy of the serous blisters on the front of the thigh; pronounced edema just below the epidermis (a. H&E, 40×); inflammatory infiltrates with eosinophils (b. H&E, 200×).

SDRIFE, or what was previously called baboon syndrome, is a drug eruption characterized by symmetrical gluteal and intertriginous erythema with no other systemic involvement following systemic exposure to a drug. The most common causative drugs are beta-lactam antibiotics, although SDRIFE has also been reported following exposure to corticosteroid, biologic, and chemotherapeutic agents [1]. Histopathology of lesional skin typically demonstrates superficial perivascular infiltrates, usually of lymphocytes or eosinophils. Other previously reported features include subcorneal pustules, vacuolar changes and hydropic degeneration in the basal cell layer with subepidermal bullae [1].

SDRIFE-like rash have rarely been reported following drug intake, as well as group A streptococcal and parvovirus B19 infections [2]. In addition, some recent reports show association with severe COVID-19 infection [3]. Drug-induced eruption and disease-associated rash are difficult to distinguish in severe COVID-19 patients because their cutaneous manifestations may be caused by increased use of drugs. For example, there are some reports on mimicking cases caused by remdesivir or by the drugs for which drug transformation test was all positive [4,5]. We experienced a mild COVID-19 patient who have any of the various signs and symptoms (e.g., sore throat, fever, and cough) but do not have shortness of breath, dyspnea, or abnormal chest imaging. To our knowledge, this is the second report of a SDRIFE-like rash in a mild COVID-19 patient for which no culprit drug was identified, following a report by Athira et al. of a patient who was positive for COVID-19 IgG antibody, with no history of drug intake prior to onset of SDRIFE-like rash [6]. Therefore, it is necessary to accumulate more data to assess the true correlation between COVID-19 and SDRIFE-like rash.