Cutaneous Myiasis of the Scalp Presenting as Bilateral Orbital Edema

DISCUSSION

Although maggots or intact larvae were not seen on presentation to the ophthalmology clinic, the clinical history and features suggest bilateral contact dermatitis, which could be due to irritant mineral oil or larval secretions. Myiasis is caused by the invasion of tissues or organs of humans or animals by dipterous larvae. Human myiasis is a rare clinical condition, but more frequently seen in tropical and subtropical areas. Hot, humid climate with inadequate sanitary conditions favors the development of this condition. Dermatitis, psychiatric illnesses, leprosy, and diabetes are some contributory factors.⁶ It is the fourth most common travel-associated skin disease, which can be divided according to the body’s tissue vulnerability. The most common and the most frequently encountered clinical form is cutaneous myiasis, while body cavity, nasopharyngeal, ocular, aural, gastrointestinal, and urogenital myiases are less common⁷ as mentioned in Table 1.

Wound myiasis occurs when fly larvae infest open wounds, which may be the result of facultative or obligatory parasites. The larvae of the housefly Malus domestica are found in dung and decaying refuse and are saprophagous. Most Sarcophagidae species that cause myiasis deposit their eggs or larvae over the host at some predisposing site, such as wounding, necrosis, or bacterial contamination.⁹ Advanced age, poor social conditions, poor personal hygiene, poor general condition, mental retardation, immobilization, diabetes mellitus, alcoholism, vascular occlusive disease, ulcerating lesions, bacterial infection of wounds and infected dermatitis, travel to endemic areas, and contact with livestock are predisposing factors for cutaneous myiasis.^7,10 Our case was also having wound myiasis, poor socioeconomic condition, poor personal hygiene, and contact with livestock though no similar case of distant cutaneous lesion of myiasis causing periorbital edema has been reported in the literature.

Contact dermatitis is the most common cause of cutaneous eyelid inflammation.¹¹ The skin over the eyelid is vulnerable to irritants and allergens because of its thinness, sensitivity, and frequent exposure to chemicals via direct application or contamination from fingers and hands^11,12 and hence may be the initial or the only presenting area with signs of contact dermatitis, while other areas of the body remain unaffected by the same exposure.¹² Contact dermatitis can be classified as allergic or irritant. The presenting features of both types are often not readily distinguishable, but patients with irritant contact dermatitis often present with greater burning and stinging compared with the characteristic pruritus of allergic contact dermatitis^12,13 as was present in our case. Contact dermatitis of the eyelid is mediated by a type IV hypersensitivity reaction in allergic contact dermatitis and by direct toxic effect in irritant contact dermatitis.¹³ It is more often caused by a product applied to the hair, nails, or face than by the products applied directly to the eyelids.¹² Thus, in our case, the patient might have touched her lids with infested nails or hands and resulted in periorbital edema.

Various differentials for the swollen red eyelid include orbital cellulitis, which is a severe infection presenting with proptosis and ophthalmoplegia and life-threatening. Less serious conditions, such as contact dermatitis, atopic dermatitis, and blepharitis, are more common causes of eyelid erythema and edema and are differentiated on the basis of clinical clues such as time course, presence or absence of irritative symptoms, scaling, and other skin findings. Discrete lid lesions like vesicles, erosions, or crusting are also important diagnostic indicators for herpes infection. Hordeola, chalazia, and furuncles are benign, self-limiting eyelid nodules, whereas malignancies require surgical excision.