Contact Dermatitis Caused by a Grass, Axonopus compressus in a Healthy Adult Male Practising Open Defaecation

Phytodermatitis is an inflammation of the skin caused by contact with plants or their constituents. A variety of cutaneous reactions, ranging from contact urticaria to irritant and allergic contact dermatitis, have been reported 1. Here we report a case of contact dermatitis due to Axonopus compressus. A 58-year-old male presented with itching over the bilateral buttocks and thighs for 2 months. Examination revealed multiple erythematous and hyperpigmented papules arranged in linear and criss-cross patterns over bilateral buttocks and the postero-lateral thighs (Figure 1a). The lesions were intensely pruritic. There was no personal or family history of atopy. A potassium hydroxide mount was negative for fungal elements. A diagnosis of irritant contact dermatitis was made, and the patient was treated with topical clobetasol propionate, oral antihistamines, and emollients. At follow-up, itching had subsided and lesions had partially healed; similar lesions recurred after 15 days. The pattern of the lesions prompted enquiry about his sanitation practices. He recently moved to a location lacking toilet facilities and was practising open defecation. A provisional diagnosis of allergic contact dermatitis due to grass exposure was made. Histopathology revealed orthokeratotic hyperkeratosis, mild irregular acanthosis, lymphocyte exocytosis, mild papillary dermal oedema, and perivascular lymphocytic infiltrate. A voucher specimen of grass was collected from Bharatpur, Angul, Odisha, India, and deposited at the Regional Plant Resource Centre Herbarium, Bhubaneswar, Odisha, India (Voucher No. RPRC 11810, Field No. 8641). The specimen was identified as carpet grass (Axonopus compressus Sw. P. Beauv.; fam. Poaceae) by Dr. C. Kalidas, Scientist, Regional Plant Resource centre, Bhuaneswar, Odisha, India; and Dr. Soumendra Kumar Naik, Professor, Department of Botany, Ravenshaw University, Cuttack, Odisha, India (Figure 2a,b), and on searching the literature, we found it is known to cause allergic contact dermatitis 2. Patch testing was done from crude extract from leaves and inflorescence of Axonopus compressus by mixing it with petrolatum jelly, and was applied over the back of the patient by using a solitary Finn chamber. The reading was taken after 48 h, which showed a positive (+) reaction (Figure 1b). Control subjects were not tested. Treatment was restarted and the patient was advised to avoid further exposure by using toilet facilities. On 1-month follow-up, all lesions had subsided without recurrence. Open defecation practice is most prevalent in India, followed by Indonesia, Pakistan, Nigeria, and Ethiopia. The prevalence of open defecation in the rural and urban populations of India is around 65% and 16%, respectively 3. Open defecation poses significant health and environmental risks and causes serious health hazards like diarrhoea and waterborne diseases. It also creates vulnerability for women and girls who are exposed to abuse and harassment during open defecation. Phytodermatitis can also be considered a health hazard related to open defecation. The four mechanisms by which plants cause dermatitis are immediate hypersensitivity, irritant or mechanical dermatitis, phytophotodermatitis, and delayed hypersensitivity. Immediate hypersensitivity presents as itching, wheals, and rarely anaphylaxis and shock. Irritant or mechanical contact dermatitis presents as erythema, oedema, papules, vesicles, and in severe cases, bullae, pustules, and ulceration. Phytophotodermatitis and allergic contact dermatitis share similar clinical presentations; however, phytophotodermatitis can be distinguished by its presence in sun-exposed areas and by the post-inflammatory hyperpigmentation that often follows 4. Other possible causes of the rash might be a mechanical injury caused by the ‘prickle hairs’ that are found on grass, and also the rust fungus present on the grass 5, 6. The clinical differential diagnosis of our case includes flagellate dermatitis, which was ruled out as there was no history of intake of bleomycin or shitake mushroom. Dermatitis artefacta was ruled out as the lesions were in non-accessible sites. Paederus dermatitis was ruled out due to the absence of vesiculation and pain. Wong et al. in their study found Axonopus compressus to cause irritant contact dermatitis, and was not more prevalent among atopic individuals 7. Koh et al. in their study found both allergic and irritant contact dermatitis to grass species like Axonopus compressus, Imperata cylindrica, Ischaemum muticum, Pennisetum purpureum, and Panicum maximum 2. This case is being reported because of the rarity of mention of grass dermatitis in the literature. Abhipsa Samal: writing – original draft. Chandan Kumar Sahoo: data acquisition and literature search. Jayashree Mohanty: manuscript review. Siddhartha Dash: conceptualization, visualization, writing – review and editing, writing – original draft. The authors have nothing to report. The authors have nothing to report. Informed written consent was taken from the patient. The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.