Abstract
Melanonychia describes black pigmentation of the nail plate that results from either melanocyte activation (such as infections, local inflammatory disorders, local trauma affecting the nail plate, numerous systemic conditions, and medications) or melanocyte hyperplasia (such as benign neoplasms or malignant tumors) or blood (resulting from a trauma-associated subungual hematoma). The black dyschromia may include not only the nail plate but also the proximal nailfold. The Hutchinson sign refers to black discoloration of both the proximal nailfold and adjacent nail plate when the underlying pigmented lesion is a malignant melanoma. The pseudo-Hutchinson sign describes these same morphologic features when the associated pigmented lesion is benign. The pseudo-pseudo-Hutchinson sign is used to describe the clinical scenario when there is non-black dyschromia of the proximal nailfold and nail plate, such as green caused by Pseudomonas aeruginosa infection or red resulting from an acute subungual hematoma. A 65-year-old man is described whose trauma-associated subungual hematoma of his left great toenail presented with a pseudo-Hutchinson sign. Sequential images of the distal toe, the proximal nailfold, and the nail plate were taken at two weeks, six weeks, 10 weeks, 14 weeks, and 18 weeks after the traumatic injury occurred. Two weeks after the injury occurred, the black discoloration of the pseudo-Hutchinson sign could be seen on the proximal nailfold and nail plate of the left great toenail; 16 weeks later, the pseudo-Hutchinson sign was not present. The black discoloration originally observed on the proximal nailfold had completely resolved; the black dyschromia of the proximal nail plate had progressed between 3 and 4 mm distally, and there was a normal-appearing nail plate on the left great toenail extending from the proximal nailfold. In addition to the Hutchinson sign, the pseudo-Hutchinson sign, and the pseudo-pseudo-Hutchinson sign, there are several conditions that are characterized by the condition, the pseudo-condition, and the pseudo-pseudo condition. The conditions include infections (such as bacterial), disorders (affecting the cardiovascular, endocrine, gastrointestinal, neurologic, ophthalmologic, or rheumatologic systems), and syndromes (that may or may not be associated with benign neoplasms or malignant tumors). In conclusion, a trauma-associated pseudo-Hutchinson sign of a 65-year-old man's left great toenail was described. The clinical observations confirmed the suspected diagnosis of the pseudo-Hutchinson sign. Additional evaluation, possibly including nail plate avulsion with an appropriate biopsy to determine the etiology of the pigmented lesion in the nail matrix and/or the nail bed, should be considered in an individual who develops features of the pseudo-Hutchinson sign that persist to exclude melanoma-associated Hutchinson sign.