Melanotic schwannoma (MS) is a rare variant of nerve sheath neoplasm that shows ultrastructural and immunophenotypical features of Schwann cells but also has cytoplasmic melanosomes and is reactive for melanocytic markers as well. Unlike conventional schwannoma, which is totally benign, MS has an unpredictable prognosis and is thought to have low-malignant potential. Herein, we present a rare case of recurrent MS in lumbar spine of a 59-year-old male.
Cytoplasm ; Humans ; Male* ; Melanosomes ; Middle Aged* ; Neoplasm Metastasis ; Nerve Sheath Neoplasms ; Neurilemmoma* ; Prognosis ; Recurrence ; Schwann Cells ; Spinal Nerves* ; Spine

The microphthalmia-associated transcription factor (MITF), has been described as the master regulator of the basic helix-loop-helix leucine zipper family, involves melanogenesis in melanocytes. MITF consists of at least six isoforms, called MITF-M, MITF-A, MITF-B, MITF-C, MITF-H, and MITF-J. Previously, we found that not only MITF-M is expressed in the human hair follicle, but also MITF-A, MITF-C, MITF-H, and MITF-J isoforms are expressed in the skin. The aim of this study was to conform the MITF isoforms expressed in human skin, and investigate novel role of MITF isoforms in the melanocytes. Expression of MITF-M and MITF-A was found in primary melanoctyes and the melanoma cell lines. Interestingly, when MITF-M and MITF-A were overexpressed in the SK-MEL-24 melanoma cells by adenoviral transfection, length of the dendrites, serves as the principal conduit for melanosomes transfer, was significantly increased in the MITF-M overexpressed cells compared with the control group, and number of the dendtrites was significantly increased in the MITF-A overexpressed cells. A signal molecule involve in actin polymerization during dendrite formation, Rac1, was increased in the SK-MEL-24 melanoma cells treated with adenoviral MITF-M and MITF-A vectors. These results suggest that MITF-M and MITF-A induce dendrite formation via Rac1 signaling in the melanocytes.
Actins ; Cell Line ; Dendrites ; Hair Follicle ; Humans ; Leucine Zippers ; Melanocytes* ; Melanoma ; Melanosomes ; Microphthalmia-Associated Transcription Factor ; Polymerization ; Polymers ; Protein Isoforms ; Skin ; Transfection

Melanogenesis is the biological process that results in the synthesis of skin pigment of melanin and it has various functions in living systems and is synthesized by the melanosome within the melanocytes. A variety of physical treatments are used to promote melanin production in the melanocytes for pigmentation control. The purpose of this study was to evaluate the intensity-dependent effect of extremely low-frequency electromagnetic fields (ELF-EMFs) on melanogenesis by melanocytes in vitro. Melanocytes were exposed to ELF-EMFs at a frequency of 50 Hz and at intensities in the range of 0.5–20 G over 4 days. The results of lactate dehydrogenase assay showed that there were no significant differences between cells exposed to 0.5 G or 2 G groups and the controls. The melanin contents increased 1.2–1.5-fold in cells exposed to ELF-EMFs and tyrosinase activity increased 1.3-fold in cells exposed to ELF-EMFs, relative to the controls. Also, exposure to ELF-EMFs was associated with activation in cyclic-AMP response element binding protein and microphthalmia-associated transcription factor (MITF) was up-regulated. Up-regulation of MITF induces the expression of melanogenesis-related markers, such as tyrosinase, tyrosinase-related protein (TRP)-1, TRP-2. In conclusion, the present study showed that the exposure to ELF-EMFs at low intensities can stimulate melanogenesis in melanocyte, and these results may be used to a therapeutic devices for inducing repigmentation in vitiligo patients.
Biological Processes ; Carrier Proteins ; Electromagnetic Fields* ; Humans ; In Vitro Techniques ; L-Lactate Dehydrogenase ; Magnets* ; Melanins ; Melanocytes* ; Melanosomes ; Microphthalmia-Associated Transcription Factor ; Monophenol Monooxygenase ; Pigmentation* ; Response Elements ; Skin ; Up-Regulation ; Vitiligo

BACKGROUND: Protease-activated receptor 2 (PAR-2) participates in various biological activities, including the regulation of epidermal barrier homeostasis, inflammation, pain perception, and melanosome transfer in the skin. OBJECTIVE: To evaluate the basic physiological role of PAR-2 in skin. METHODS: We investigated PAR-2 expression in human epidermis, skin tumors, and cultured epidermal cells using western blot and immunohistochemical analysis. Additionally, we examined the effect of the PAR-2 agonist, SLIGRL-NH2, on cultured keratinocytes. RESULTS: Strong PAR-2 immunoreactivity was observed in the granular layer of normal human skin and the acrosyringium of the eccrine sweat glands. In contrast, weak PAR-2 immunoreactivity was seen in the granular layer of callused skin and in the duct and gland cells of the eccrine sweat glands. Interestingly, PAR-2 immunoreactivity was very weak or absent in the tumor cells of squamous cell carcinoma (SCC) and syringoma. PAR-2 was detected in primary keratinocytes and SV-40T-transformed human epidermal keratinocytes (SV-HEKs), an immortalized keratinocyte cell line, but not in SCC12 cells. SV-HEKs that were fully differentiated following calcium treatment displayed higher PAR-2 expression than undifferentiated SV-HEKs. Treatment of cultured SV-HEKs with PAR-2 agonist increased loricrin and filaggrin expression, a terminal differentiation marker. CONCLUSION: Our data suggest that PAR-2 is associated with terminal differentiation of epidermis and eccrine sweat glands.
Blotting, Western ; Bony Callus ; Calcium ; Carcinoma, Squamous Cell ; Cell Line ; Epidermis* ; Homeostasis ; Humans ; Inflammation ; Keratinocytes ; Melanosomes ; Pain Perception ; Receptor, PAR-2 ; Skin ; Sweat Glands* ; Sweat* ; Syringoma

BACKGROUND: Progressive macular hypomelanosis, a disease of uncertain etiology, was first described by Guillet et al. in 1988. It is characterized by asymptomatic hypopigmented macules and patches that appear on the trunk and upper extremities. It is a relatively recently described disorder and more case reports are needed. OBJECTIVE: The purpose of the study was to document the clinicopathologic and ultrastructural features of progressive macular hypomelanosis in Korean patients. METHODS: Patients who presented to our hospital and were diagnosed with progressive macular hypomelanosis from July 2009 to June 2014 were enrolled in this study. Skin scrapings were taken for fungal tests, and skin biopsy specimens from lesional and normal skin were obtained. Sections of the skin biopsies were stained with hematoxylin and eosin, Brown and Brenn Gram stain, and Fontana-Masson stain, and they were incubated with a panel of immunohistochemical reagents used to identify melanocytes, namely, gp-100, melan-A, and microphthalmia-associated transcription factor. The tissues from two patients were also examined using electron microscopy. RESULTS: Over the course of 5 years, 16 patients presented with ill-defined hypopigmented macules on their trunks and upper extremities. The mean age of the patients was 28.4+/-9.0 years and the male to female ratio was about 1 : 4. Histopathologically, lesional skin showed a reduced level of pigmentation, while the number of melanocytes was preserved. None of the patients showed bacterial colonization of the pilosebaceous units. Electron microscopy demonstrated smaller and less melanized melanosomes in the lesional keratinocytes. CONCLUSION: Progressive macular hypomelanosis is a hypopigmentary disorder that is characterized by a loss of melanosomes without damage to the melanocytes. Although there are several reports that describe a possible relationship between Propionibacterium acnes and progressive macular hypomelanosis, it remains unclear.
Biopsy ; Colon ; Eosine Yellowish-(YS) ; Female ; Hematoxylin ; Humans ; Hypopigmentation* ; Indicators and Reagents ; Keratinocytes ; Korea ; Male ; MART-1 Antigen ; Melanocytes ; Melanosomes ; Microphthalmia-Associated Transcription Factor ; Microscopy, Electron ; Pigmentation ; Propionibacterium acnes ; Skin ; Upper Extremity

No abstract available.
Adult* ; Humans ; Melanosomes* ; Pilot Projects* ; Skin* ; Zebrafish*

BACKGROUND: Melanocytes are present in both basal epidermis and hair follicles. Melanocyte stem cells have been found in hair follicle bulge. During embryogenesis, the outer cells of the bulge differentiate into the sebaceous gland (SG) and proliferate. OBJECTIVE: To identify and determine the distribution and morphological characteristics of melanocytes in human SGs. METHODS: A total of 171 biopsy specimens of face and scalp were studied. Of these specimens, 103 samples contained SGs. We conducted a retrospective review of slides stained with H&E, F-M, anti-S100, anti-c-kit, anti-HMB-45, anti-CD1a, anti-MITF, and anti-tyrosinase. The presence and distribution of melanocytes in human SGs was also evaluated by electron microscopy. In addition, melanocytes were isolated from SGs for primary culture. RESULTS: S-100-positive cells were observed mainly at the periphery of SGs in 34 of 54 specimens. We did not find F-M-positive and HMB-45-positive cells in SGs. CD1a-positve cells were identified in two specimens. We also found c-kit-, MITF-, and tyrosinase-positive cells in SGs. Electron micrograph showed the presence of melanocytes in the suprabasal portion of SGs. These melanocytes showed fewer melanin-containing granules than the melanocytes of basal epidermis. However, the individually distributed melanosomes in suprabasal melanocytes were larger than those in epidermal melanocytes. Primary culture of melanocytes derived from SGs showed morphologically homogeneous, slender cell bodies with few dendrites. CONCLUSION: Our study confirms the presence of non-melanogenic melanocytes and Langerhans cells in human SGs. In addition, the characteristics of the melanocytes in SGs were found to be different from those of the epidermal melanocytes.
Biopsy ; Dendrites ; Embryonic Development ; Epidermis ; Female ; Hair Follicle ; Humans ; Langerhans Cells ; Melanocytes* ; Melanosomes ; Microscopy, Electron ; Pregnancy ; Retrospective Studies ; Scalp ; Sebaceous Glands* ; Stem Cells

We investigated the inhibitory effects of hesperidin on melanogenesis. To find melanosome transport inhibitor from natural products, we collected the structural information of natural products from Korea Food and Drug Administration (KFDA) and performed pharmacophore-based in silico screening for Rab27A and melanophilin (MLPH). Hesperidin did not inhibit melanin production in B16F10 murine melanoma cells stimulated with alpha-melanocyte stimulating hormone (alpha-MSH), and also did not affect the catalytic activity of tyrosinase. But, hesperidin inhibited melanosome transport in melanocyte and showed skin lightening effect in pigmented reconstructed epidermis model. Therefore, we suggest that hesperidin is a useful inhibitor of melanosome transport and it might be applied to whitening agent.
Biological Agents ; Computer Simulation ; Epidermis ; Hesperidin* ; Korea ; Mass Screening ; Melanins ; Melanocytes ; Melanoma ; Melanosomes* ; Monophenol Monooxygenase ; Skin ; United States Food and Drug Administration

Melanin is produced in melanocytes and stored in melanosomes. In spite of its beneficial sun-protective effect, abnormal accumulation of melanin results in esthetic problems. Hydroquinone, competing with tyrosine, is a major ingredient in topical pharmacological agents. However, frequent adverse reactions are amongst its major limitation. To solve this problem, several alternatives such as arbutin, kojic acid, aloesin, and 4-n-butyl resorcinol have been developed. Herein, we classify hypopigmenting agents according to their mechanism of action; a) regulation of enzyme, which is subdivided into three categories, i) regulation of transcription and maturation of tyrosinase, ii) inhibition of tyrosinase activity, and iii) post-transcriptional control of tyrosinase; b) inhibition of melanosome transfer, and c) additional mechanisms such as regulation of the melanocyte environment and antioxidant agents.
Arbutin ; Chromones ; Glucosides ; Hydroquinones ; Hypopigmentation ; Melanins ; Melanocytes ; Melanosomes ; Monophenol Monooxygenase ; Pyrones ; Resorcinols ; Tyrosine

Pigmentation is induced by production of melanin in specialized organelles termed melanosomes and by transfer of these organelles from melanocytes to surrounding keratinocytes. The chemical basis of melanogenesis is relatively well known but the mechanism of melanosome transfer is not well studied. Various pigmentary disorders and cosmetic applications require the use of depigmenting agents. Currently available topical agents used for the reduction of pigmentation mainly include tyrosinase inhibitors and/or melanocyte-cytotoxic agents. Recently, several agents have been introduced to inhibit melanosome transfer from melanocytes to keratinocytes. However, an experimental model for melanosome transfer is not well established. In this study, a simple assay method using flow cytometry is described.
Cosmetics ; Flow Cytometry ; Keratinocytes ; Melanins ; Melanocytes ; Melanosomes ; Models, Theoretical ; Monophenol Monooxygenase ; Organelles ; Pigmentation