A Case of Dapsone-induced Mild Methemoglobinemia with Dyspnea and Cyanosis.

Dear Editor, Dapsone is a dual-function drug with antimicrobial and antiprotozoal effects and anti-inflammatory features (1). In dermatology, it is a first choice for conditions such as leprosy, IgA pemphigus, dermatitis herpetiformis, and linear IgA bullous dermatosis, or an adjunctive treatment for, e.g. bullous pemphigoid (BP) and pemphigus vulgaris (1). However, dapsone is associated with some adverse effects, including methemoglobinemia (1). Methemoglobin (MetHb) concentrations of less than 15% usually cause no symptoms in patients with normal hemoglobin concentrations (2). Herein, we report the case of a patient with BP who developed dyspnea because of dapsone-induced methemoglobinemia that was as mild as 4.7%. A 93-year-old man was diagnosed with BP based on skin manifestations (Figure 1, a and b), histopathological findings (Figure 1, c and d), and anti-BP180 NC16A antibody titer determined by chemiluminescence enzyme immunoassay (279 U/mL) 3 years earlier. His comorbidities included diabetes mellitus, chronic heart failure, right pleural effusion, and brain infarction. The patient had been successfully treated with oral prednisolone, so the steroid was tapered to 4 mg/day. The blisters recurred, however, and new ones kept developing even though the prednisolone was increased to 25 mg/day. Dapsone (75 mg/day) was begun as adjunctive treatment, and new blister formation ceased. At one week from dapsone initiation, the patient developed dyspnea, and his oxygen saturation as measured by pulse oximetry decreased to 88% on room air. At presentation, his blood pressure was 118/78 mmHg, the heart rate was 95 beats/minute, and axillary temperature was 36.3 °C. Neurological examination and consciousness findings remained unchanged compared with findings before dyspnea onset. Chest examination showed normal breath and heart sounds, but lip and peripheral cyanosis was present. Blood tests revealed a white blood cell count of 12,920/µl; red blood cells, 370×104/µl; hemoglobin, 11.7 g/dl; and CMV antigenemia (or C7-HRP), negative. Chest CT and echocardiography indicated no remarkable change compared with imaging from one year earlier. Arterial blood gas analysis showed a pH of 7.454, PaO2 63.1 mmHg, PaCO2 35.4 mmHg, HCO3- 24.3 mmol/L, SaO2 92.4%, and MetHb of 4.7%. These findings indicated a saturation gap (difference between SpO2 and SaO2) induced by MetHb. Upon cessation of dapsone, MetHb levels and SpO2 returned to normal and the dyspnea resolved, implicating dapsone in the methemoglobinemia (Figure 1, e). Differential diagnoses were pulmonary disease, heart disease, neuromuscular disease, sepsis, and drug intoxication. These possibilities were ruled out by the physical examination, drug history, vital signs, blood tests, and chest CT and echocardiography. In normal individuals, MetHb levels are less than 1% (2). Healthy patients with normal hemoglobin concentrations develop cyanosis at MetHb level of 15-20%, dyspnea at 20-50%, and coma at 50-70%, and die at more than 70% (2). However, patients with hematologic disease, acidosis, or cardiopulmonary diseases, for example, present with symptoms even with MetHb levels less than 15% (2,3). We inferred that our patient presented with dyspnea even under mild methemoglobinemia because he had anemia, chronic heart failure, and right pleural effusion. The occurrence of dapsone-induced methemoglobinemia with obvious symptoms is rare (1,4). Clinicians should be aware that methemoglobinemia symptoms are influenced not only by MetHb concentrations but also by comorbidities.

IgG/IgA pemphigus reactive with desmoglein 1 with additional undetermined reactivity with epidermal basement membrane zone.

IgG/IgA pemphigus is an extremely rare subset of pemphigus, showing anti-keratinocyte cell surface antibodies of both IgG and IgA classes. Herein, we describe a unique case of IgG/IgA pemphigus with clinical features of edematous erythema and peripheral vesiculopustules. Histopathology showed the presence of subcorneal pustules and acantholytic blisters in the mid-epidermis with neutrophilic infiltration and eosinophilic spongiosis. Direct immunofluorescence of perilesional skin showed both IgG and IgA deposits to keratinocyte cell surfaces and unusual granular deposits of IgG, IgM, and C3 along basement membrane zone. On enzyme linked immunosorbent assay , the auto-antibodies were found to be reactive to desmoglein 1 antigen. Various clinical, histopathological, and immunological findings in our case overlapped with the features of IgA pemphigus, pemphigus herpetiformis, and pemphigus foliaceus. These findings indicate that IgG/IgA pemphigus may be a transitional form between IgA pemphigus and pemphigus herpetiformis, and thus provides insight into the pathogenicity of this rare disorder.

Assessment of the therapeutic benefit of dexamethasone cyclophosphamide pulse versus only oral cyclophosphamide in phase II of the dexamethasone cyclophosphamide pulse therapy: a preliminary prospective randomized controlled study.

BACKGROUND: Dexamethasone cyclophosphamide pulse (DCP) therapy is an established mode of treatment for pemphigus in India. AIMS: To assess the therapeutic benefit of additional DCPs (phase II, consolidation phase) versus immediate oral cyclophosphamide, usually used in phase III (maintenance phase), after initial DCP therapy (phase I) and to assess which laboratory test (DIF or ELISA) will reflect the clinical relapse best. METHODS: Nineteen newly recruited patients of pemphigus vulgaris (PV) received monthly DCPs in phase I and were then randomized into two groups. Group A (10 patients) received monthly DCPs for nine months and Group B (nine patients) received only oral cyclophosphamide for nine months. Direct immunofluorescence (DIF) and enzyme-linked immunosorbent assay (ELISA) were tested before starting DCP regimen, and at 0,3,6,9 months after randomization. RESULTS: Clinical relapse by the end of follow-up period occurred in only one patient in each group. In these cases, DIF became (again) positive before the relapse. No statistically significant difference between the two groups was found at three, six and nine months by ELISA indices and DIF grading. CONCLUSION: Although the DCP regimen is the standard therapy for pemphigus in India, we found no difference in the clinical outcome between patients receiving nine DCPs in phase II and patients shifted directly from phase I to III. Periodic testing using DIF and Dsg ELISA were found to be useful to monitor disease activity and predict a relapse. Further large scale studies are required to assess if patients can be shifted directly from phase I to III and maintained only on oral cyclophosphamide.