A 19-year-old male presented to the Family Medicine clinic with pain and slight swelling on the right cheek. On examination a small tender mass was palpable under the skin on the right cheek. The patient also mentioned being hit by a piece of wood during construction work.
The physician decided to perform a quick POCUS soft tissue exam. The image and video below were obtained.
What is the best possible diagnosis?
A. Foreign body
B. Edema
C. Cellulitis

The diagnosis is foreign body.
Explanation
A well-defined linear echogenic foreign body is seen embedded in the soft tissue. There is a surrounding well defined hypoechoic region which is consistent with granuloma formation. The foreign body was removed under ultrasound guidance.
Foreign body granuloma develop as a reactionary response to foreign bodies such as wood, metal fragments or any other exogenous material that get embedded during skin penetrating trauma. See the labeled image below.

References
1. Boyse, T.D., Fessell, D.P., Jacobson, J.A., Lin, J., van Holsbeeck, M.T., Hayes, C.W. US of Soft-Tissue Foreign Bodies and Associated Complications with Surgical Correlation. RadioGraphics, 2001, 21(5): 1251-1256. https://doi.org/10.1148/radiographics.21.5.g01se271251
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