Diagnosis: Felon
The most likely diagnosis is a felon (Option A), which is an abscess of the distal pulp space of the fingertip following penetrating trauma with a stick. 1
Clinical Reasoning
Why Felon is the Correct Diagnosis
Mechanism of injury matches perfectly: Penetrating trauma from a stick directly inoculates bacteria into the closed pulp space of the distal phalanx, which is the classic mechanism for felon development 1, 2
"Swollen bulb" is pathognomonic: A felon presents with tense swelling of the entire fingertip pulp due to the complex system of fibrous septa that compartmentalize the infection, creating the characteristic bulbous appearance 1
Intact nail bed excludes nail-related pathology: The preserved nail bed rules out primary nail bed injury and makes paronychia (which affects periungual tissues) less likely 1
Extreme pain is expected: Felons are characteristically extremely painful because the fibrous septa limit swelling, causing rapid pressure buildup in a confined space 1
Why Other Options Are Incorrect
Paronychia (Option B) affects the nail fold and periungual tissues, not the pulp space of the fingertip. It presents with swelling and erythema around the nail margins, not a swollen "bulb" of the entire fingertip 3, 1
Onychomycosis (Option C) is a chronic fungal infection causing nail thickening, discoloration, and friable texture over weeks to months—completely incompatible with acute traumatic presentation 3
Cellulitis (Option D) would present with spreading erythema and edema without the localized, tense, bulbous swelling confined to the distal pulp space that characterizes a felon 1
Critical Management Considerations
Urgent Surgical Intervention Required
Felons require prompt surgical drainage to prevent devastating complications including osteomyelitis of the distal phalanx, flexor tendon sheath infection, and potential digit loss 1, 2
Delayed treatment leads to destruction of fibrous septa and allows spread into bone or flexor tendon sheath, potentially requiring partial amputation 2
Common Pitfall to Avoid
Do not attempt conservative management with antibiotics alone—the compartmentalized nature of the pulp space prevents adequate antibiotic penetration, and the infection will progress rapidly without surgical decompression 1, 2