Differentials
Herpetic whitlow
SIGNS / SYMPTOMS
Herpetic whitlow can involve any area of the fingertip or periungual tissues, but only when it causes inflammation of the nail folds does it result in acute paronychia. Therefore, herpes is a known cause of acute paronychia, but herpetic whitlow is a differential in the causes of a painful fingertip.
Blistering and increased pain differentiate this from bacterial acute paronychia.[1][10]
INVESTIGATIONS
Direct fluorescent antibody: positive staining of the herpes simplex virus (HSV).
Tzanck smear: multinucleated giant cells, inclusion bodies, nuclear molding.
Culture: HSV.
Polymerase chain reaction: HSV.
Arthropod bite or sting
SIGNS / SYMPTOMS
Itch, history of bite or travel differentiate this from acute paronychia.[1]
INVESTIGATIONS
Biopsy will show typical changes of dense inflammatory infiltrate with eosinophils.
Traumatic injury
SIGNS / SYMPTOMS
History of injury differentiates this from acute paronychia.[1]
INVESTIGATIONS
X-ray for underlying foreign bodies or fracture.
Squamous cell carcinoma or other malignancy such as amelanotic melanoma
SIGNS / SYMPTOMS
Lack of any response to therapy differentiates this from chronic paronychia.[1]
INVESTIGATIONS
Biopsy shows malignant cells.
Myxoid cyst
SIGNS / SYMPTOMS
Swelling/translucency over nail folds differentiates this from chronic paronychia.[1]
INVESTIGATIONS
Needling with viscous fluid or transillumination, biopsy, MRI.
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