Myiasis under Dermatoscope: The Hidden Story.

Abstract

Case 1 A 12-year-old boy accompanied by his father presented with boggy swelling of the scalp with multiple overlying ulcerations for the past 15 days. His father revealed a history of head trauma due to slippage in rainwater 15 days back. On examination, multiple 1 × 1 cm to 1 × 2 cm ulcers were presented over the vertex with oozing of blood and serous fluid [Figure 1a]. The underlying scalp was boggy and tender. Cervical lymphadenopathy was present. Rest of the mucocutaneous and systemic examination was normal. KOH was negative. The ulcers probably resulted from infestation and secondary bacterial infection.Figure 1: (a) Multiple oozing ulcers present over the scalp. (b) Ulcer showing minute creamy white structures within the fluidCase 2 A 5-year-old girl was brought by her mother with multiple ulcers over bilateral upper limb and lower limb for the past 20 days. The lesions started spontaneously as erythematous nodules, suggestive of furunculosis. On examination, multiple ulcers with serosanguineous drainage were noted. There was movement of fluid inside the ulcer [Figure 1b]. Dermoscopy [Dinolite AM413ZT; polarising mode; 50-150X] was done for both cases. It showed multiple, mobile, creamy white-colored structures with reniform centres. Each Reniform centre had three pairs of hairpin loop-like structures [Figure 2a]. A diagnosis of myiasis was considered and turpentine oil was flushed over the lesions. Within 15 minutes, the larvae started moving upwards and captured on dermoscopy as white translucent cylindrical mobile organisms. Each larva had multiple bands of arrow-shaped brown pigmentation [Figure 2b]. The larva was extracted and an ex-vivo dermoscopy was done which showed a fusiform semi-translucent larva. The posterior segment of the larva had tracheal trunk whereas the spiny mouth parts were present on the anterior end. Multiple, spiny, arrowhead-shaped structures arranged in bands were present on the body and blood meal was seen within the body [Figure 2c]. All the visible larvae were manually extracted and the patient was given turpentine oil application along with systemic antibiotics.Figure 2: (a) Creamy white structures (Black arrow) with brown reniform centres (blue arrow). Note the three pairs of hairpin loop-like structures (Dinolite 413ZT; ×50). (b) Creamy white cylindrical larva with multiple bands of spiny arrow-shaped structures (Dinolite 413ZT; ×50). (c) Ex-vivo dermoscopy showing tracheal trunk on the posterior segment (blue arrow) while the spiny mouth parts were present on the anterior end (red arrow). Note multiple spiny arrowhead-shaped structures arranged in bands (black arrow) and blood meal within the body (Dinolite 413ZT; ×150)Myiasis is an infestation by dipterous larvae. In cutaneous myiasis, two clinical forms have been described – wound myiasis and follicular (furuncular) myiasis.[1] Dermoscopic features of myiasis has been described with handheld contact dermatoscopes.[2345] The breathing spiracles has been described as bird's feet-like structures.[4] The dark brown spiny structures have been described as thorn crown.[4] In our observation, the breathing spiracles were visible as reniform structures with three hairpin loop-like structures on either side. The variation in observation may be because of higher magnification provided by the USB dermatoscopes and larvae of different family of flies causing myiasis. Whereas Dermatobia hominis is the major cause of myiasis in the American continent, Chrysomya bezziana is the most common etiology in the Indian subcontinent. Entomodermoscopy is an evolving field of dermoscopy. Though a good clinical evaluation with or without magnifying lens can reveal presence of larva in most cases, the utility of dermoscopy as a tool for easy detection of larvae and their complete extraction encouraged us to report these findings. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.