Dermatologic Manifestations of Paronychia Clinical Presentation

The patient's history is crucial in determining the possibility of more serious underlying systemic conditions that may predispose the patient to paronychia. These underlying conditions may include diabetes, obesity, hyperhidrosis, immunologic defects, polyendocrinopathy, and drug-induced immunosuppression. Note the following:

• Acute paronychia: Patients with acute paronychia often present with a history of minor trauma to the fingertip or nail manipulation, intentional or not. The presenting complaints are pain, tenderness, and swelling in one of the lateral folds of the nail.
• Chronic paronychia: Generally, patients report symptoms lasting 6 weeks or longer. Inflammation, pain, and swelling may occur episodically, often after an exposure to water or a moist environment.

Acute paronychia physical findings are as follows:

• The affected area often appears erythematous and swollen.
• In more advanced cases, pus may collect under the skin of the lateral fold.
• If untreated, the infection can extend into the eponychium, in which case, it is called eponychia.
• Further extension of the infection can lead to the involvement of both lateral folds as it tracks under the nail sulcus; this progression is called a runaround infection.
• In severe cases, the infection may track proximally under the skin of the finger and volarly to produce a concomitant felon. The fulminant purulence of the nail bed may generate enough pressure to lift the nail off the nail bed.

Chronic paronychia physical findings are as follows:

• Swollen, erythematous, and tender nail folds without fluctuance are characteristic of chronic paronychia.
• Eventually, the nail plates become thickened and discolored, with pronounced transverse ridges.
• The cuticles and nail folds may separate from the nail plate, forming a space for the invasion of various microorganisms.

Acute paronychia causes are as follows:

• Acute paronychia usually results from a traumatic event, however minor, that breaks down the physical barrier between the nail bed and the nail; this disruption allows the infiltration of infectious organisms.
• Acute paronychia can result from seemingly innocuous conditions, such as hangnails, or from activities, such as nail biting, finger sucking, manicuring, or artificial nail placement.
• Staphylococcus aureus is the most common infecting organism. Organisms, such as Streptococcus and Pseudomonas species, gram-negative bacteria, and anaerobic bacteria are other causative organisms.
• Acute (and chronic) paronychia may also occur as a manifestation of other diseases, such as pemphigus vulgaris. Although instances of nail involvement in pemphigus vulgaris are rare, they can be severe, involving multiple digits and hemorrhage.

Chronic paronychia causes are as follows:

• Chronic paronychia is primarily caused by the yeast fungus Candida albicans.
• Other rare causes of chronic paronychia include bacterial, mycobacterial, or viral infection; metastatic cancer; subungual melanoma; squamous cell carcinoma; and Raynaud disease. Therefore, benign and malignant neoplasms should always be excluded when chronic paronychia does not respond to conventional treatment.
• Chronic paronychia most often occurs in persons whose hands are repeatedly exposed to moist environments or in those who have prolonged and repeated contact with irritants such as mild acids, mild alkalis, or other chemicals. People who are most susceptible include housekeepers, dishwashers, bartenders, and swimmers.

Other conditions associated with abnormalities of the nail fold that predispose individuals to chronic paronychia include psoriasis, mucocutaneous candidiasis, and drug toxicity from medications such as retinoids, epidermal growth factor receptor inhibitors (cetuximab), and protease inhibitors.^{[1, 2]} Of particular interest is the antiretroviral drug indinavir, which induces retinoidlike effects and remains the most frequent cause of chronic paronychia in patients with HIV disease.