Inflammatory Foot Dermatoses: The Correlation Among Morphological Patterns, Histopathological Findings, and Patch Test Positivity

Objective In this study, we aimed to investigate the correlation between the clinical diagnosis, histological diagnosis, and patch test positivity among patients with foot dermatoses receiving treatment at the Department of Dermatology, MES Medical College, Perinthalmanna. Methodology A hospital-based cross-sectional observational diagnostic evaluation was carried out from January 1, 2019, to December 31, 2019, among 44 patients with foot dermatoses who met the inclusion criteria. A thorough general physical and cutaneous examination was performed to determine the type, extent, and morphology of lesions after obtaining the written informed consent; sociodemographic information and a thorough recording of patient history were gathered. In all cases, a potassium hydroxide (KOH) mount, skin biopsy, and patch testing were performed. Additionally, pus culture and sensitivity tests were conducted in pertinent cases. Results Our study found that the most prevalent foot dermatosis, based on clinical diagnosis, was allergic contact dermatitis (ACD) foot, affecting 26 patients (59.0%). This was followed by plantar psoriasis, observed in 13 patients (29.5%), and lichen planus, present in two patients (4.5%). The predominant histological diagnosis was ACD foot in 11 patients (25.0%), followed by plantar psoriasis in 10 patients (22.7%), spongiotic dermatitis in seven patients (15.9%), atopic dermatitis (AD) and psoriasiform dermatitis in four patients (9.1%) each, and tinea pedis in two patients (4.5%). The sensitivity of patch testing in detecting ACD foot was 90.91%, whereas its specificity was 57.58%. The positive and negative predictive values (PPV and NPV) were 41.67% and 95.0% respectively. Conclusions Based on our findings, histopathological evaluation is a highly effective diagnostic technique for foot dermatoses, as it demonstrated exceptional diagnostic accuracy (p<0.001). The sensitivity of patch testing in identifying ACD of the foot was 90.91% (p<0.05). This highlighted the usefulness of patch testing as a confirmatory diagnostic tool along with histopathological evaluation for precise diagnosis of ACD of the foot. While laboratory testing can increase diagnostic precision, it cannot replace a clinical examination.