Nails can be challenging for even seasoned dermatology providers, but a familiarity with “the good, the bad, and the ugly” of nail presentations can help improve diagnosis and treatment. In his session at the Society of Dermatology Physician Assistants Annual Summer Dermatology Conference 2021 in Chicago, IL, Brad Glick, DO, MPH, FAOCD, provided attendees with new confidence in treating nails in their daily practice.

The good of nails is that anatomy can provide clues to a diagnosis. Growth, for example, can be either accelerated or reduced, signaling psoriasis or onychomycosis, respectively. In addition, the nail matrix anatomy can help differentiate between diagnoses. “Remember that the undersurface of the nail plate is formed by the distal matrix, the midportion is from the midmatrix, and the proximal portion of the nail matrix form the top of the nail plate. That’s really important [to remember] in evaluating longitudinal melanonychia and other pigmented disorders,” explained Dr Glick. Melanocytes are found in the distal matrix but not in the nail bed, thus pigment in the nail bed is not typically melanocytic in origin.

Site of nail damage is critical to identify. The proximal matrix is affected by Beau’s lines, pitting, longitudinal riding and fissuring, and trachyonychia. However, if there is involvement of the proximal and distal matrices, then onychomadesis, koilonychia, and nail thinning may be diagnoses. The nail bed can be affected by onycholysis, subungual hyperkeratosis, apparent leukonychia, and splinter hemorrhages.

The bad of nails is the presentation of diseases. Dr Glick discussed the various presentations of nail conditions and signs, emphasizing for many of the presentations to think systemic disease if multiple digits show nail abnormalities. Medications can also induce nail changes, said Dr Glick. In particular, chemotherapeutic agents are often at fault.

The nails also offer clues to dermatologic diseases. Psoriasis, for example, often affects multiple nails, particularly finger nails, showing irregular pitting, salmon patch/oil drop signs, and onycholysis with erythematous borders. Parakeratosis pustulosa, however, is psoriasiform lesions but tends to be exclusive to children and limited to one nail. Lichen planus (LP) is rare, with nail presentation occuring in up to 10% of patients, and shows onychorrhexis, plate thinning, and dorsal pterygium and affects several nails.

“The ugly of the nail unit are malignancies,” said Dr Glick. Nail unit malignancies can be easy to miss because of some diagnostic conundrums, but he recommended that “any non-healing lesion impacting the functional nail unit should get a biopsy.” Providers should follow the ABCDEFs of melanoma identification.

Reference
Glick B. Nails. Presented at: Society of Dermatology Physician Assistants Annual Summer Dermatology Conference 2021; July 22-25, 2021; Chicago, IL.