A Case of the Swollen Finger

Author: Kayla Prokopakis, DO 

Peer Reviewer: Matthew Negaard, MD CAQ-SM

Final Editor: Alex Tomesch, MD

18 year-old male presents with a painful and swollen left thumb. He removed a splinter from his finger a few days ago however 2 days after removal, he began to experience edema and pain that has progressively gotten worse.

Image 1: Picture courtesy of Rosh Review [1]. 

1. What is your diagnosis?

2.  How does this condition develop?

3. What do you need to rule out? What are other diagnoses that should be considered in the Emergency Department?

4. What is your management? 

-- See below for answers --

1. What is your diagnosis?

The patient has a felon. A felon is a subcutaneous abscess in the finger pulp. The most common location for a felon is the thumb or the index finger [2-5]. 

• Pearl: The most common organism leading to a felon is staph aureus [2,5]

2.  How does this condition develop?

The mechanism for the development of a felon can occur secondary to penetration from a foreign body, minor trauma from biting the fingernail, local spread from a paronychia, or idiopathic. There are microcompartments in the finger and when an infection arises, the swelling can be severe enough to cause compartment syndrome. [2-5].

 

• Pearl: A felon differs from a paronychia as a felon is in the pulp and usually presents on the pad of the finger while a paronychia is in the epidermis along the nail fold [2,5]. 

3. What do you need to rule out? What are other diagnoses that should be considered in the Emergency Department?

Flexor tenosynovitis! This is potentially a finger and hand threatening infection. The location of swelling can differentiate between flexor tenosynovitis and a felon. the swelling in a felon does not extend proximal past the distal interphalangeal joint [4,5]. If it does, there is concern that the infection has spread into the flexor sheath and IV antibiotic and emergent ortho consult is necessary. 

• Pearl: To identify flexor tenosynovitis utilize the Kanavel signs [4,5]. 

4. What is your management?

The management of a felon is similar to that of an abscess. Initial management can include warm compresses and supportive care. The definitive treatment is incision and drainage [2-5]. The use of antibiotics after drainage is controversial but if they are prescribed, should cover staph aureus. 

• Pearl: The incision made for an incision and drainage should be made distal to the distal interphalangeal joint and should be on the ulnar side for digits 2-4 and the radial side for thumb and 5th digit [2]. A digital block should be considered for adequate analgesia during the procedure.

See EM:RAP HD for video of the felon incision and drainage procedure.

REFERENCES

1. Rosh, Adam. Rosh Review website. Accessed April 22, 2021. https://www.roshreview.com/. 

2. Stapczynski, JS, Tintinalli, JE. Musculoskeletal Disorders: Felon. Tintinalli's emergency medicine: A comprehensive study guide, 8th Edition. New York, NY: McGraw-Hill Education; 2016: 1924.

3. Nardi NM, McDonald EJ, Schaefer TJ. Felon. In: StatPearls. Treasure Island (FL): StatPearls Publishing; July 20, 2020. PMID: 28613683.

4. Koshy JC, Bell B. Hand Infections. J Hand Surg Am. 2019;44(1):46-54. doi:10.1016/j.jhsa.2018.05.027. PMID: 30017648.

5. Rerucha CM, Ewing JT, Oppenlander KE, Cowan WC. Acute Hand Infections. Am Fam Physician. 2019;99(4):228-236. PMID: 30763047.

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