Acquired Localized Longitudinal Pachyonychia and Onychomatrical Tumors: A Comparative Study of Onychomatricomas and Onychocytic Matricomas

This study compared 4 cases of onychocytic matricomas (OCMs) with 5 cases of onychomatricomas (OMs), focusing on their clinical and histopathologic characteristics. Both types of tumors exhibited a localized longitudinal band pattern of thickened nail plates, but OCMs showed a V-shaped keratogenous epithelial tumor with a papillomatous growth pattern and small honeycomb cavities, while OMs displayed large honeycomb cavities. The study highlighted the importance of nail clipping in diagnosing onychomatrical tumors, suggesting that larger cavity dimensions (>0.15 mm) indicate benign growths, potentially avoiding unnecessary excisional procedures. Conversely, smaller cavities (<0.10 mm) should prompt further biopsy to exclude malignancy.