Pachyonychia Congenita Workup

Updated: Feb 08, 2019
  • Author: Saira J George, MD; Chief Editor: William D James, MD  more...
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Laboratory Studies

Molecular DNA analysis in pachyonychia congenita reveals missense mutations, deletion mutations, substitution mutations, and other mutations of keratin genes K6a, K6b, K16, and K17.

Oral leukokeratosis is to be differentiated from leukoplakia or cancer either by performing an oral biopsy or by recognizing its presence in patients with other symptoms of pachyonychia congenita.

Microscopy or culture of nail clippings or scrapings can help differentiate candidal or fungal onychomycosis from pachyonychia.


Histologic Findings

Histologic examination of plantar hyperkeratotic plaques reveals an acanthotic epidermis with parakeratosis and orthokeratosis compatible with rapid keratinocyte proliferation and differentiation. Cytologic atypia is not seen. Immunostaining shows positive immunostaining of K14, as would be expected along with K6, K16, K17 in the basal cell layer. In the suprabasal layers, K6, K16, K17, and K14 staining persists and K10 staining appears. [12, 19, 20]

Electron microscopy on palmar or plantar plaques shows thickened and clumped intermediate filaments, as well as enlarged keratohyaline granules. In the broadened granular layer, thick masses of tonofilaments and large, irregular keratohyaline granules are present. In the spinous layer, thick masses of tonofilaments are found at the periphery of the cells.