The bar code like hairs seen here in our patients
The bar code-like hairs seen here in our patients are characterized by irregularly interrupted hairs with normally pigmented and paler narrowed intervals on dermoscopy. As Slowinska et al have reported that the fungal hyphae such as M. canis in patients with tinea capitis perforate the hair thymidylate synthase inhibitors at some points to produce the conidia on the hair surface, we hypothesize that the narrowed paler parts of the bar code-like hairs most likely represent the points of fungal penetration from within. Furthermore, we have also observed that the zigzag hairs consistently bend at these narrowed paler parts of the infected hair shafts, which suggest its structural weakness (Figure 4A, black arrow).
Dermoscopy is a fast, readily available test that can be performed at the bedside, and recognition of these dermoscopic features is simple. Because topical antifungal treatment would be ineffective in eradicating follicular fungal infection, it is important that dermatologists are aware of these findings and commence systemic antifungal therapy for patients with tinea capitis. Further study is required to show that the presence of bar code-like hairs is an additional reliable finding of fungal infection of the hair follicles.
Introduction Malignant peripheral nerve sheath tumors (MPNSTs; also known as “malignant schwannoma”, “neurofibrosarcoma”, and “neurosarcoma”) are rare neoplasms of ectomesenchymal origin, with an incidence of 0.001% in the general population. Approximately 50% of cases are associated with neurofibromatosis type I (NF-1). Most MPNSTs are found in deep soft tissue along the major peripheral nerve trunk. However, superficial forms of this tumor have been identified. Superficial MPNST is defined as a lesion predominantly located in the dermis or subcutis without contact with the fascia. Some authors have suggested that the association with NF-1 is less common in superficial forms of MPNST than in their deep counterparts. Most NF1-associated MPNSTs appear to arise within pre-existing plexiform neurofibromas, which are deeply seated. Non-NF-1 MPNSTs in association with a solitary neurofibroma and presenting as a superficial form have been identified. Herein, we report a case of MPNST arising in a location of previously diagnosed recurrent neurofibroma.
Case report A 71-year-old woman presented to our clinic with a 2.5 × 1.5 cm skin-colored tumor on her left upper back in May 2009 (Figure 1A). She had no clinical signs of NF-1, such as café-au-lait spots, axillary freckling, multiple cutaneous neurofibromas, and iris hamartomas (Lisch nodules) on physical examination. A family history of NF-1 or past history of radiation exposure were absent. An excisional biopsy showed some mucinous material admixed with faintly eosinophilic collagen extending in various directions, interlaced with spindle cells with elongated wavy nuclei in the dermis (Figure 1B and C). The spindle cells were positive for S-100 and neurofibroma was diagnosed (Figure 1D). There was recurrence of the skin tumor at the same site 9 months later (Figure 2A). Another excisional biopsy was done and showed a myxoid tumor embedded in thick collagen bundles in the mid to deep dermis. The tumor consisted of spindle cells with elongated wavy nuclei arranged in a whorled pattern and faintly eosinophilic collagen in myxoid stroma (Figure 2B and C). The spindle cells were positive for S-100 (Figure 2D). Recurrent neurofibroma was diagnosed. Three years later, a rapidly growing skin tumor emerged at the same site (Figure 3A). The patient received total excision of the skin tumor. The pathologic report showed an ill-defined tumor in the dermis and subcutaneous tissue, measuring 5 cm × 3.8 cm × 3.5 cm (Figure 3B). Microscopically, the tumor was composed of spindle cells in a focally myxoid stroma with an obvious transition from the area of typical neurofibroma to the hypercellular area (Figures 3C and 4A). The hypercellular area consisted of atypical, hyperchromatic spindled cells with frequent mitotic figures (Figure 4B). Immunohistochemical staining revealed that the tumor cells were positive for S-100 (Figure 4C and D). Based on these findings, we made a diagnosis of superficial MPNST arising from solitary neurofibroma. The resected margins were close to the tumor cells (2–3 mm). No further follow-up information is available owing to the recent diagnosis.