A retrospective study on the direct immunofluorescence findings in pigmented purpuric dermatosis.

BACKGROUND: Pigmented purpuric dermatosis (PPD) is characterized by grouped petechiae, purpuric macules, and pigmentation in the bilateral lower extremities. It runs a chronic and relapsing course. Pathophysiology is poorly understood, but it has been proposed to be an immune-complex disease or capillaritis. This study aimed to determine the incidence and patterns of positive direct immunofluorescence (DIF) findings in patients with clinically and histopathologically confirmed PPD. The association between DIF deposition type and clinical profile was also analyzed. METHODS: Patients with a clinical and histopathologic PPD diagnosis who had undergone DIF studies at a tertiary medical center with attached dermatopathology and immunofluorescence diagnostic centers between January 2002 and December 2021 were included in this study. Data on age, sex, disease duration, comorbidities, and drug intake were collected from medical records. RESULTS: There were 65 patients who satisfied the inclusion criteria. Among them, 58 (89%) had at least one positive finding and 53 (82%) were vascular deposition of immunoglobulin (Ig), complement, or fibrinogen. The most common vascular deposition was fibrinogen (71%) followed by C3 (62%), IgM (18%), IgA (6%), and IgG (3%). Fibrinogen deposition was associated with hypertension (p < 0.03). There was no association between vascular DIF deposition of IgG, IgA, and C3, with age, sex, comorbidities, disease duration, and drug history. CONCLUSION: The most common DIF findings in PPD were vascular deposition of fibrinogen and C3, with or without Ig presence. DIF findings supported a vascular origin in PPD but not an immune complex-mediated disease. Hypertension was associated with fibrinogen deposition and may play a role in its pathophysiology.

Blastomycosis-like pyoderma: A pitfall for the misdiagnosis of squamous cell carcinoma.

Blastomycosis-like pyoderma is a rare cutaneous disease presenting as solitary or multiple verrucous or ulcerated plaques and nodules in a susceptible patient. The diagnostic criteria include characteristic verrucous plaques with pustules and elevated borders, histopathologic findings of pseudoepitheliomatous hyperplasia with abscesses, growth of at least one bacterium in tissue culture, and exclusion of other infectious sources. This report describes a case of a 62-year-old man with poorly controlled type 2 diabetes mellitus who presented with plaques, nodules, and ulcers in both groins and the right ankle. The patient was initially misdiagnosed with multiple squamous cell carcinomas and underwent several operations. A review of the pathology slides revealed pseudoepitheliomatous hyperplasia with multiple dermal abscesses, while repeated wound and tissue cultures were positive for coagulase-negative Staphylococcus. Blastomycosis-like pyoderma was diagnosed. The patient was subsequently treated with culture-guided prolonged antibiotic therapy followed by intralesional steroid injection, which led to gradual resolution of the lesions.