The second term fibropapilliferum

is used to highlight th

The second term fibropapilliferum

is used to highlight the mixed fibroepithelial nature of this neoplasm, which forms multiple rudimentary nail units. These nail units construct multiple nail plates that join together and form a single thick nail plate. According to nail anatomy, 2 types of POP are described: POP of the apical matrix/eponychium, with a pseudo-condylomatous SCH727965 ic50 pattern, and POP of the ventral matrix with a foliated pattern in transverse sections and a fibrokeratoma-like pattern in the longitudinal sections. Suggestions for the evaluation and clinical management of localized longitudinal pachyonychia are proposed. On histology of a nail clipping, 2 patterns with clinical significance can be individualized. A horizontal alignment of large cavities indicates POP of the ventral matrix. A haphazard arrangement of smaller cavities in the nail plate, including an arrangement in the inferior two-thirds of the nail clipping, should prompt a biopsy of the distal ventral matrix to rule out a malignant lesion. In the setting of the masked nail tumor, a clinical subtype with some significance can be individualized, the subungual keratotic nodule growing rapidly. Three nail bed tumors are discussed within this latter group. Two new clinicopathological variants of subungual keratoacanthoma are described, and a new nail bed tumor is discussed:

the infundibulocystic nail bed squamous cell carcinoma. The absence of striking nuclear atypia and the giant cystic to multicystic pattern distinguishes infundibulocystic nail ARRY-470 Z-IETD-FMK inhibitor bed squamous cell carcinoma from follicular infundibulocystic squamous cell carcinoma. The last section proposes a classification of folliculogenic nail bed tumors. The follicular microcysts of the nail bed have previously been called subungual epidermoid inclusions or onycholemmal cysts, but the term follicular microcysts of the nail bed is more pertinent, because of the multiple lines of follicular differentiation (infundibular, tricholemmal, apocrine, and sebaceous) seen in their benign and malignant counterparts. Absent in a large portion

of the normal nail bed, the follicular microcysts seem to have a peculiar propensity for the formation of tumors that vary in maturity from simple follicular microcystic hyperplasia associated with acquired longitudinal melanonychia to microcystic nail bed hamartoma and microcystic nail bed carcinoma (the so-called onycholemmal carcinoma).

The concluding tables emphasize the key and essential histological features required to make the diagnosis of site-specific nail tumors and guide appropriate therapy. The author proposes to categorize subungual tumors into 2 types: subungual skin tumors (including subungual skin metastasis from internal malignancies) and nail tumors. Nail tumors can be accurately classified using a combined clinical and histogenetic approach.

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