With interest we read the recent article on methemoglobinemia by Chan et al.[1] Through this letter, we would like to add few additional comments regarding methemoglobinemia and its relevance in medicine practice with regards to food poisoning.

BACKGROUND: Oral lichen planus (OLP) is an immune-mediated potentially malignant disorder of the oral cavity. Dysplastic OLP has an altered cytogenic profile and can progress into oral squamous cell carcinoma. The epidemiology of OLP is well-described in several relatively large series from various geographic locations, whereas such series from southern India is rare. The aim of the present study was to determine the epidemiology of OLP in a cohort of South Indian population. METHODS: All the case data records of 29,606 patients who visited Mar Baselios Dental College and Hospital, Kerala, India from 2014 to 2015 were retrospectively reviewed. For data review, 122 patients of OLP were selected Estimated were type, number, and location of lesions, clinical manifestation, age of the patient, gender, onset and duration of lesion, stressful life style, habits, skin involvement and associated systemic illness, and presence/absence of dysplasia. RESULTS: When the distribution of OLP among the gender was considered, we found more prevalence in females than males. Fifty-seven percent of patients were associated with stressful lifestyle. Reticular lichen planus was the most common clinical subtype found. Bilateral buccal mucosal was the common site, when the distribution of sites of OLP were compared (P < 0.05). Hypersensitivity reaction was frequently associated with systemic illness with OLP (P < 0.05). Anaplasia was found among 5% of lichen planus lesions. CONCLUSIONS: OLP patients had high incidence of hypersensitivity reactions and 5% of OLP lesions showed anaplasia. Long term follow-up is necessary to monitor the recurrence, prognosis, and malignant transformation of OLP.
Anaplasia ; Carcinoma, Squamous Cell ; Cohort Studies* ; Epidemiology* ; Female ; Follow-Up Studies ; Geographic Locations ; Humans ; Hypersensitivity ; Immune System Diseases ; Incidence ; India ; Lichen Planus ; Lichen Planus, Oral* ; Life Style ; Male ; Mouth ; Prevalence ; Prognosis ; Recurrence ; Retrospective Studies* ; Skin

BACKGROUND: The role of tumour inflammation and the dysplastic epithelial-stromal interactions on the nature of collagen fibres in the extracellular matrix of dysplastic epithelium is not fully understood. The present study was aimed to evaluate and compare the inflammation and pathological stromal collagen (loosely packed thin disorganized collagen) present in mild, moderate and severe epithelial dysplasias with that of inflammatory fibrous hyperplasias. The basement membrane intactness of epithelial dysplasias was also evaluated to determine if dysplastic epithelial mesenchymal interaction has any role in the integrity of stromal collagen in epithelial dysplasia. METHODS: Oral epithelial dysplasias, inflammatory fibrous hyperplasia and normal oral mucosal samples were used for the study. Packing, thickness and orientation of collagen fibres in mild, moderate and severe grades of oral epithelial dysplasias (n = 24), inflammatory fibrous hyperplasia (n = 8) and normal oral mucosal samples (n = 8) were analysed based on the polarisation of collagen fibres in picrosirius red polarising stain under polarising microscope. RESULTS: All the grades of epithelial dysplasias showed greenish yellow birefringence confirming the presence of loosely arranged pathological collagen in the presence of moderate inflammation. All the cases of inflammatory fibrous hyperplasia showed red polarisation hue and moderate inflammation. A statistically significant difference was found in the packing and orientation of collagen when epithelial dysplasias and inflammatory fibrous hyperplasia were compared (P < 0.01). When the intactness of basement membrane integrity was compared in all the groups of epithelial dysplasia, a statistically significant result was obtained (P < 0.05). CONCLUSIONS: Presence of significant amount of loosely packed thin disoriented collagen even in mild epithelial dysplasia suggests that tumourigenic factors are released to connective tissue stroma much earlier than expected. Hence we suggest considering the integrity of extracellular matrix collagen, intactness of basement membrane and inflammation associated with dysplasia along with the anaplasia of epithelial cells in the microscopic assessment of dysplastic epithelium.
Anaplasia ; Basement Membrane ; Birefringence ; Collagen* ; Connective Tissue ; Epithelial Cells ; Epithelium ; Extracellular Matrix* ; Hyperplasia* ; Inflammation* ; Microscopy* ; Mouth Mucosa