Breast - nonmalignant
Parasites
Myiasis

Author: Jaya Ruth Asirvatham M.B.B.S., M.D. (see Authors page)
Editor: Julie M. Jorns, M.D.

Revised: 28 July 2017, last major update August 2014

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Myiasis breast

Cite this page: Myiasis. PathologyOutlines.com website. http://pathologyoutlines.com/topic/breastmyiasis.html. Accessed November 20th, 2017.
Definition / general
  • Infestation of body by larva of several genera of Diptera (flies with 2 wings)
  • Larvae usually occupy skin and subcutis but potentially any organ
Terminology
  • Most common: human botfly (Dermatobia hominis)
  • Others: Cochliomyia hominovaroxiz, Chrysomya bezziana, Cordylobia anthrophaga
Epidemiology
Pathophysiology
  • Adult flies are usually attracted to host orifices and unattended open wounds where they lay eggs
  • Some species infect living tissue (e.g. botfly)
  • May lay eggs on soiled clothes, larvae may develop and can penetrate intact skin (e.g. green bottle fly)
  • Botfly larvae creates a cavity with an opening (like a long neck bottle) after penetrating the skin and grow into a mature fusiform shape up to 3 cm in diameter
  • A firm red subcutaneous nodule / furuncle is formed in 2 - 3 weeks
Clinical features
  • May cause fever, local inflammation and bleeding and superimposed bacterial infection
  • Cause abscess and rarely granulomatous response to dead larvae
  • May be a secondary infection in fungating breast carcinoma
  • Can mimic breast carcinoma (East Afr Med J 1999;76:115)
  • Often multiple infestations in breast
  • Also affects lips of breast fed infants (Int J Dermatol 2006;45:1069)
  • Can be misdiagnosed as cellulitis, mosquito bites, herpes etc.
Laboratory
  • Genus / species identification: comparing certain morphological structures on the larvae (spiracles, mouthparts, cephalopharyngeal skeleton, cuticular spines)
  • Travel history helpful
Radiology description
  • May form an ill defined mass with calcification (Radiology 2001;218:517)
  • US may show a hyperechoic mass representing the larva surrounded by a hypoechoic halo representing the cavity
  • Larval movement may be noted
Radiology images

Images hosted on other servers:

Various images

Structure in the axillary region

Case reports
Treatment
  • Needs surgical removal
  • Removal of larva may be facilitated by plugging the orifices which forces the larva to come out of its tunnel to breathe
Clinical images

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Breast lesion with tumbu fly larvae

Sinuses after extraction of the larva

Extracted tumbu fly larvae

One week after extraction

Gross images

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Extracted from dog

Microscopic (histologic) description
  • Chronic granulomatous response, dead larvae
Microscopic (histologic) images

Images hosted on other servers:

H&E, various images

Botfly - respiratory spiracles

Granulomatous response around a spine

Differential diagnosis
  • Ticks: have legs and mouth and don't burrow deeply into skin
  • Tunga penetrans: flea with legs, almost always involves feet, has cuticle > 20 microns, lacks a spine