I would say it is a deep tissue hematoma.

Therapeutic exercise: moving toward function - Google Books Resultby Carrie M. Hall, Lori Thein Brody - 2005 - Medical - 787 pages
When a deep-tissue hematoma occurs, ecchymosis may or may not be seen on the skin surface. For example, quadriceps femoris contusions frequently result in ...
books.google.com/books?isbn=0781741351... -
Wound care: a collaborative practice manual - Google Books Resultby Carrie Sussman, Barbara M. Bates-Jensen - 2007 - Medical - 720 pages
The hypothesis that exogenous application of US to the adjacent skin can promote absorption and resolution of hematoma (deep tissue injury) or venous ...
books.google.com/books?isbn=0781774446... -

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Note added at 32 mins (2009-10-19 18:58:57 GMT)
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Or haematoma in the UK.

I think the author refers to patients that may develop a tension hematoma with respiratory obstruction after thyroid surgery despite the presence of a drain .
Check some references:
http://www.google.com.ar/search?hl=es&source=hp&q=tension he...

Results 1 - 10 of about 5,130 for expanding hematoma thyroid surgery. (0.28 seconds)
Search Results

1.
Outpatient thyroid surgery is safe and desirable - Elsevier
There were no instances of hemorrhage or expanding hematomas, .... Is suction drainage an effective means of preventing hematoma in thyroid surgery? ...
linkinghub.elsevier.com/retrieve/pii/S0194599806032608 - Similar
by DJ Terris - 2007 - Cited by 19 - Related articles
2.
Revision Thyroid Surgery – Technical Considerations - Elsevier
27 Nov 2008 ... After thyroid surgery, the patient should be closely observed in the recovery room, and any expanding hematoma is a dire emergency. ...
linkinghub.elsevier.com/retrieve/pii/S0030666508000960 - Similar
by AR Shaha - 2008 - Related articles
Show more results from linkinghub.elsevier.com
3.
The effectiveness of FloSealŪ matrix hemostatic agent in thyroid ...
devastating complication secondary to thyroid surgery. An unrecognized or rapidly expanding hematoma can cause airway compromise and asphyxiation, ...
www.springerlink.com/index/a38236715040g103.pdf - Similar
by M Testini - 2009 - Related articles - All 2 versions

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Note added at 1 day14 hrs (2009-10-21 08:47:50 GMT)
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http://209.85.229.132/search?q=cache:IPnjKphY_bQJ:yourtotalh...


Potential risks with thyroid surgery

Thyroid surgery can offer significant health benefits. However, it also involves some risks of which patients should be aware. Less than 2 percent of people who undergo thyroid surgery experience these complications, according to the American Thyroid Association.

Thyroid surgery includes risk of damage to the recurrent and external laryngeal nerves that control the vocal cords. This can result in hoarseness or a weakening of the voice.

Surgery also can damage the parathyroid glands, which control the level of calcium in the blood. Damage to the parathyroid glands may require the patient to take calcium medication to ensure that levels of calcium in the bloodstream remain normal. Patients are urged to contact their physician if they experience tingling or twitching after the operation. This reaction can indicate that a person’s calcium level is low, which may occur if the parathyroid gland is damaged.

In some cases, bleeding occurs that may lead to acute respiratory distress. Rarely, postoperative bleeding can cause an expanding hematoma (swelling of blood) that may constrict the airway. Sudden swelling in the wound area may indicate bleeding.

Surgery may result in a visible scar on the neck. In addition, thyroid surgery involves all of the usual risks involved with any surgery, including infection and adverse reaction to anesthesia. Redness and drainage from the wound area may indicate infection.


BTW
I think my original answer of "haematoma resulting in severe restrictive airway" was pretty much OK.

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Note added at 1 day14 hrs (2009-10-21 08:49:09 GMT)
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Where are all the medical experts when you need them eh?? Probably looking after their patients :)

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Note added at 1 day14 hrs (2009-10-21 09:07:34 GMT)
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PLUS

Cirugía Plástica Ibero-Latinoamericana - Lesiones oculares y ...
- [ Translate this page ]
3a: ejemplo de lesión transfixiante del párpado superior .... on the visual system following sudden retrobulbar expanding lesions - an experimental model. ...
scielo.isciii.es/scielo.php?pid=S0376...script=sci_arttext - Cached - Similar
by JC Zambrano - Related articles - All 2 versions

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Note added at 6 days (2009-10-26 13:29:02 GMT)
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Re your last comment - fair enough, but I would be grateful to hear of any feedback from your client, particularly as I spent so long looking into this:)