Inverted Follicular Keratosis: Dermoscopic and Reflectance Confocal Microscopic Features

Abstract

Inverted follicular keratosis (IFK) is a rare benign tumor which usually appears as a firm papule on the face. The diagnosis is generally made by histopathology because the clinical appearance is difficult to differentiate from other lesions. Dermoscopic features of IFK have not been established to date. Herein we describe the dermoscopic findings of 4 cases of IFK. Radial peripheral hairpin vessels surrounded by a whitish halo arranged around a central white-yellowish amorphous area were observed in 3 cases, and glomerular vessels were present in the central area of one of them. The fourth case also presented a central white amorphous area but showed arborizing vessels. Reflectance confocal microscopy (available in 1 case) revealed a broadened honeycomb pattern, epidermal projections and hairpin and glomerular vessels. To our knowledge this is the first case series describing the dermoscopic features of inverted follicular keratosis and the first confocal microscopy description of this entity.

Dermoscopy of inverted follicular keratosis: study of 12 cases

“…The second most common dermoscopic pattern of IFK is an amorphous, yellowish‐white, central area surrounded by hairpin vessels with a white halo, in a radial arrangement. This pattern was present in 33.3% of our cases, and it is the most common pattern reported in the isolated cases previously published in the literature . The amorphous central area is defined as a structureless homogenous zone, whitish to yellowish, occupying the central area of the tumour.…”

“…Dermoscopy is a noninvasive technique that has greatly improved the diagnostic accuracy of pigmented and nonpigmented skin tumours . To our knowledge, the dermoscopic features of IFK have been described in only a few cases . We report the dermoscopic features of a series of IFK with their different patterns, which could improve the clinical diagnostic accuracy of this tumour.…”

Yellow and orange in cutaneous lesions: clinical and dermoscopic data

“…57 Calcification is seen in 80% of lesions, 57 and when it occurs superficially the dermatoscopy of this tumour sometimes shows yellowish lobules. 58 The presence of keratin in other tumour lesions explains that we can identify the yellow colour in dermoscopy in some seborrhoeic keratosis, actinic keratosis, keratoacanthomas, squamous cell carcinoma, Bowen's disease, inverted follicular keratosis 59 or melanocytic congenital naevus. The presence of yellowish crusts explains the yellow colour dermoscopy in other lesions as some pyogenic granulomas.…”

A case of inverted follicular keratosis with onset since childhood

“…The IFK originates from the follicular infundibulum, and the clinical manifestations are isolated papules, nodules, or plaques with a hole-like opening at the centre of the top portion and a keratin-filled interior; these papules are generally observed on the face or neck of elder male patients over 50 y of age and occasionally on the torso or limbs [1]. To our knowledge, the reports on this disease onset since childhood were rare.…”