Discussion in 'Spot Diagnosis' started by neo_star, Mar 4, 2013.
What's your diagnosis for this case ?
Answer: [SIZE=+1]Multiple furunculoid myiasis[/SIZE]
of the case .......
A 4-year-old girl, who had just arrived from Bolivia, presented with furunculous lesions on the scalp. The nodules had appeared 7 days before and the area was itchy and painful.
Physical examination revealed a large inflammatory, nodular plaque that occupied the whole vertex of the scalp. There were several pores, each about 1 centimeter in diameter, from which exuded serosanguineous discharge. A great number of living larvae was seen.
Moreover, the child was febrile and exhibited regional lymphadenopathy. Complete blood count showed eosinophilia.
occlusive dressing with paraffin oil was applied for 24 hours, following which the occlusive dressing was removed, the hair cut and the wounds cleaned, the furunculous nodules were opened and the larvae extracted carefully. Partial approximation of the wound was performed by a pediatric surgeon, but the center closed by secondary intention. Microbiology analysis confirmed the diagnosis of myiasis and identified the larvae (Dermatobia hominis), and the subspecies (Cochliomyia hominivorax).
During a follow-up of 6 months, the girl has not shown any new lesions.
Cutaneous myiasis is easy to diagnose and treat if clinicians are aware of the condition. Because of widespread travel, physicians may encounter this infestation in patients living in geographical regions where the condition is rare.
Dermatobia hominia lives predominantly in warm, moist areas such as lowland forests, but can also be found in mountainous regions. The subspecies Cochliomyia hominivorax, an obligatory larval parasite, is one of the most important myiasis-causing flies.
Adult flies capture other insects and deposit 10 to 50 eggs on them. The vector in turn bites the host; the larvae, sensing the increase in temperature, immediately detach themselves and quickly burrow into subcutaneous tissues. There they feed and grow for approximately 6 to 8 weeks. The larvae emerge on maturity, fall to the ground, and pupate into adult flies.
As the larvae grow, a subcutaneous mass becomes evident. A pore, called a punctum, is present in the center of the mass and is used for ventilation and excretion of waste. Serosanguineous fluid can be expressed and sudden paroxysmal episodes of severe, sharp pain is usual. For obvious reasons the infestations have a predilection for exposed surfaces.
The diagnosis is mainly clinical. The most important clues to the diagnosis are a history of recent travel to an endemic area, adjacent healing lesions on the skin, pruritus, and a sensation of movement under skin or sudden pains. The diagnosis is confirmed by the extraction of the larvae.
Histopathological examination shows a small cavity in the dermis, containing the developing larva. Surrounding this is a heavy infiltrate of mixed inflammatory cells, which include lymphocytes, histiocytes, occasional giant cells, and plasma cells.
The furuncle-like appearance of the lesion is the reason why Dermatobia infestation is very often mistaken as common pyoderma. Other differential diagnoses include epidermoid cyst, tungiasis, cutaneous larva migrans, and cutaneous leishmaniasis.
The most important complications in man are bacterial superinfection (cellulitis, abscess formation, osteomyelitis) and tetanus. Cerebral myiasis as a result of infestation of the skin covering the fontanels of infants is a rare, but life-threatening condition.
Treatment involves removal of all larvae in their entirety; any remnant may provoke an inflammatory response. The successful use of an occlusive dressing in combination with manual extraction has been described in the literature.
The use of topical or oral ivermectin to treat severe cases of myiasis has been published. The use of this molecule paralyzes and then kills the larvae. This allows rapid alleviation of pain and makes the extraction of the larvae easier.
[SIZE=+1] Multiple furunculoid myiasis on the scalp of a child [/SIZE]
M YÃ©benes, C MuÃ±oz, M SÃ¡bat, L Palacio, B San Vicente, FJ TraverÃa, J Luelmo
Dermatology Online Journal 13 (2: 13 ) [SIZE=-1]
Departments of Dermatology, Pediatricsand Pediatric Surgery, Hospital Parc TaulÃ, Sabadell[/SIZE]
Some additional points from CDC - FAQs on Myiasis
How did I get myiasis?
You may have gotten an infection from accidentally ingesting larvae, from having an open wound or sore, or through your nose or ears. People can also be bitten by mosquitoes, ticks, or other flies that harbor larvae. In tropical areas, where the infection is most likely to occur, some flies lay their eggs on drying clothes that are hung outside.
How can I prevent infection with myiasis?
Take extra care going to tropical areas and spending a lot of time outside. Cover your skin to limit the area open to bites from flies, mosquitoes, and ticks. Use insect repellant and follow Travelers Health guidelines.
In areas where myiasis is known to occur, protect yourself by using window screens and mosquito nets.
In tropical areas, iron any clothes that were put on the line to dry.
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