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The Shapiro xanthogranuloma is a histopathologic form of xanthogranuloma that shows closely packed monomorphous cells, which can extend into the subcutaneous fat; it usually lacks routine diagnostic features of xanthogranuloma. Herein we describe two cases of Shapiro xanthogranuloma occurring in a neonate and in an infant, which were initially thought to be hematologic malignancies. One patient's presentation as a "blueberry muffin baby" added to the diagnostic confusion. Pediatric dermatologists, dermatologists, and dermatopathologists need to be aware of the Shapiro xanthogranuloma and its clinicopathologic features to avoid misdiagnosis of a hematopoietic malignancy in neonates and infants. [ABSTRACT FROM AUTHOR]

Mucinous nevus (MN) is a rare, benign, cutaneous hamartoma that may be congenital or acquired. There are admixed CD34-positive fibroblasts and a few factor XIIIa-positive dendritic cells.3 Many cases show an acanthotic epidermis with elongation of the rete ridges and hyperkeratosis, similar to an epidermal nevus. 4 Oiso N, Kimura M, Kawada A. Follicular mucinous nevus: a possible new variant of mucinous nevus. [Extracted from the article]

The follicular bulge is a stem cell niche where the basal layer of the outer root sheath (ORS) abuts the arrector pili muscle insertion site in both murine and human hair follicles.1-3 Hair follicle stem cells found at the level of the bulge localize to the basal layer of the ORS and characteristically stain for keratins 15, 17, and 19.2,3 Prior studies have recognized an uncommon structure termed the "follicular trochanter" which was described as an epithelial protrusion of the ORS in anagen follicles.4 Follicular trochanters tend to be located near the bulge region of the hair follicle and can serve as a histologic marker for the bulge.4 On exam of 144 healthy human hair follicles from 12 individuals, 8% of randomly sectioned hair follicles demonstrated trochanters.4 While follicular trochanter function is not well established, it is hypothesized that these protrusions may reflect "snapshots" of distinct developmental stages in ORS remodeling during the hair cycle.4 These structures prominently express the stem cell markers, CD200 and keratin 15 (K15).4 In this report, we describe the "fibrotic trochanter" in which a trochanter is encased in fibrotic tissue in cicatricial alopecias, in particular central centrifugal cicatricial alopecia (CCCA). To address whether fibrotic trochanters were more common in CCCA, we analyzed the number and size of fibrotic trochanters in three scarring alopecias: CCCA, LPP, and DLE. [Extracted from the article]