Ultrasonographic features and clinical pathological of liver metastasis in patients with melanoma / 中华肿瘤杂志

Objective: To investigate the ultrasonographic features and clinical pathological of liver metastasis in patients with melanoma. Methods: Thirteen patients with liver metastasis from melanoma treated in Tianjin Medical University Cancer Institute and Hospital from 2013 to 2019 were selected, and their ultrasonographic and clinicopathological characteristics were analyzed retrospectively. Results: Eleven of the 13 patients had multiple liver lesions. The maximum diameter of the lesions was (5.89±2.73) cm. Five cases of lesions were mixed echo (3 cases with high melanin content), 4 cases of lesions were hyperechoic (3 cases with low melanin content), 3 cases of lesions were hypoechoic (all with high melanin content), 1 case of lesions were equal echo (with high melanin content). The lesions in 11 patients had clear boundaries, while other 2 patients lacked the clear borders. Cystic areas were present in the lesions of 3 patients. Six cases had irregular lesions (lobulated), and 7 cases had regular lesions (round, oval). There were acoustic halos around the lesion in 9 cases and smooth and uneven acoustic halos in 5 cases. The results of immunohistochemistry showed that 11 cases were positive for S-100, HMB45 and Melan-A. One patient was not tested for HMB45, while S-100 and Melan-A were positive. One patient did not undergo Melan-A test, while S-100 and HMB45 were positive. Conclusion: Most of the liver metastases of melanoma are mixed echo or hyperechoic, most of them are nodular with clear boundaries combined with vocal halo, and a few of the lesions have cystic areas.

Immunohistochemical Markers in the Differential Diagnosis of Melanoma and Nevus in Humans

SUMMARY: Immunohistochemistry allows in situ detection of cell and extracellular components through specific antibodies. The objective was to compare the immunohistochemical expression patterns of the S-100, HMB-45 and MART-1 proteins for differential diagnosis of malignant melanoma and melanocytic nevus in human skin biopsies. Thirty-nine biopsies of human tissue were used. They were divided into two groups: 19 in malignant melanoma and 20 in melanocytic nevi. Next, the samples were fixed with paraformaldehyde and processed following the protocol for inclusion. Then, immunohistochemical staining was performed. Finally, the histological and qualitative analysis of the samples was carried out. S-100, HMB-45, and MART-1 markers showed positive immunoreaction in melanoma biopsies. HMB-45 marker was generally present with weaker expression than S-100 and MART-1 in melanocytic nevus biopsies. No expression pattern was observed which specifically associates one or more markers with some types of histopathological diagnosis. Immunohistochemistry is fundamental in differential diagnosis of melanomas and melanocytic nevi. However, there is no antibody or set of antibodies which allows unequivocal diagnosis between melanoma and nevus. It is therefore necessary to analyze with care the expression pattern and location of the lesion using standard morphological characteristics.

RESUMEN: La inmunohistoquímica permite la detección in situ de componentes celulares y extracelulares a través de anticuerpos específicos. El objetivo de nuestro estudio fue comparar los patrones de expresión inmunohistoquímica de las proteínas S-100, HMB-45 y MART-1 para el diagnóstico diferencial de melanoma maligno y nevo melanocítico en biopsias de piel humana. Se utilizaron treinta y nueve biopsias de tejido humano, las que fueron divididas en dos grupos: 19 en melanoma maligno y 20 en nevos melanocíticos. A continuación, las muestras se fijaron con paraformaldehído y se procesaron siguiendo el protocolo convencional para su inclusión. Luego, se realizó la tinción inmunohistoquímica. Finalmente, se realizó el análisis histológico y cualitativo de las muestras. Los marcadores S-100, HMB- 45 y MART-1 mostraron inmunorreacción positiva en biopsias de melanoma. El marcador HMB-45 estuvo generalmente presente con una expresión más débil que S-100 y MART-1 en biopsias de nevo melanocítico. No se observó ningún patrón de expresión que asocie específicamente uno o más marcadores con algunos tipos de diagnóstico histopatológico. La inmunohistoquímica es fundamental en el diagnóstico diferencial de melanomas y nevos melanocíticos. Sin embargo, no existe ningún anticuerpo o panel de anticuerpos que permita un diagnóstico inequívoco entre el melanoma y el nevo. Por tanto, es necesario analizar con cuidado el patrón de expresión y la localización de la lesión utilizando características morfológicas estándar.

Atypical proliferative nodule in congenital melanocytic nevus with dural invasion: a case report

Here we report a case of a focal atypical proliferative nodule (PN) arising from a congenital melanocytic nevus (CMN). Diagnosis was challenging because it had both benign and malignant clinical features. Unusual histopathology, immunohistochemistry, and intraoperative findings of this atypical PN are discussed. A 5-year-old girl was admitted for a congenital 5× 5 cm sized scalp mass. This hemangioma-like soft mass showed biphasic characteristics such as a slow, gradual, and benign increase in size but worrisome dural invasion with cranial bone defect. We removed the scalp mass with clear resection margins. Interoperatively, we found that the cranial bone defect had already filled. Histopathologic examination showed CMN with focal atypical PN. The nodule showed sharp demarcation and cellular pleomorphism. However, in immunohistochemical study, Ki-67 proliferation index and expression levels of protein S-100 and Melan-A were very low. These were unusual findings of atypical PNs. Despite her worrisome preoperative radiologic features, she showed an indolent clinical course compatible with previously reported biologic behavior. The patient underwent follow-up inspection with magnetic resonance imaging every 6 months for up to 3 years. The nodule appeared to be stationary at the last visit.

TFE3-Expressing Perivascular Epithelioid Cell Tumor of the Breast

Perivascular epithelioid cell tumor (PEComa) is a very rare mesenchymal tumor with a distinctive morphology and immunophenotype. PEComas usually harbor TSC2 alterations, although TFE3 translocations, which occur in MiT family translocation renal cell carcinoma and alveolar soft part sarcoma, are also possible. We recently experienced a case of PEComa with TFE3 expression arising in the breast. An 18-year-old female patient presented with a right breast mass. Histologically, the tumor consisted of epithelioid cells with alveolar structure and showed a diffuse strong expression of HMB45 and TFE3. TSC2 was preserved. Melan A and smooth muscle actin were negative. To our knowledge, this is the first Korean case of PEComa of the breast that intriguingly presented with TFE3 expression.

Development of Vitiligo-Like Depigmentation after Treatment of Lentigo Maligna Melanoma with 5% Imiquimod Cream

A 69-year-old man presented with a black irregular patch on his left cheek. Skin biopsy revealed lentigo maligna melanoma in situ. He was treated via partial excision of the melanoma, followed by the application of 5% imiquimod cream every other night for 6 to 8 hours. The patient experienced severe local inflammation accompanied by burning, edema, and erythema, as well as oozing and crusting. The patient discontinued using the imiquimod cream after 15 applications because of the inflammation. Depigmentation was noted in the treated area 3 months after the initiation of treatment with imiquimod cream. Histological examination using Melan-A staining of the depigmented area revealed an absence of melanocytes, which is consistent with vitiligo. The depigmented lesions improved considerably after a 5-year follow-up, and there was no recurrence of melanoma.

An Intrarenal Adrenocortical Carcinoma Arising in an Adrenal Rest

We describe a case of a 61-year-old Korean man who was diagnosed with renal cell carcinoma that was discovered on abdominopelvic computed tomography obtained after the patient complained of back pain. A radical nephrectomy was performed, and the surgical specimen showed a relatively well-circumscribed and yellowish lobulated hard mass. Microscopically, the tumor showed sheets and nests of hypercellular pleomorphic cells with thick fibrous septation, frequent mitoses, and areas of adrenal cortical-like tissue. Immunohistochemical staining revealed that the tumor cells were positive for inhibin-α, vimentin, synaptophysin, and melan A. It also revealed that the tumor cells were negative for pan-cytokeratin, epithelial membrane antigen, paired box 8, α-methylacyl-coenzyme A racemase, CD10, cytokeratin 7, carbonic anhydrase 9, c-Kit, renal cell carcinoma, transcription factor E3, human melanoma black 45, desmin, smooth muscle actin, S-100, chromogranin A, CD34, anaplastic lymphoma kinase, and integrase interactor 1. Based on these histopathological and immunohistochemical findings, we diagnosed the tumor as intrarenal adrenocortical carcinoma arising in an adrenal rest. Several cases of intrarenal adrenocortical carcinoma have been reported, although they are very rare. Due to its poor prognosis and common recurrence or metastasis, clinicians and pathologists must be aware of this entity.

Hepatic perivascular epithelioid cell tumor (PEComa): a case report with a review of literatures

Hepatic perivascular epithelioid cell tumors (PEComas) are very rare. We report a primary hepatic PEComa with a review of the literature. A 56-year-old women presented with a nodular mass detected during the management of chronic renal failure and chronic hepatitis C. Diagnostic imaging studies suggested a nodular hepatocellular carcinoma in segment 5 of the liver. The patient underwent partial hepatectomy. A brown-colored expansile mass measuring 3.2×3.0 cm was relatively demarcated from the surrounding liver parenchyma. The tumor was mainly composed of epithelioid cells that were arranged in a trabecular growth pattern. Adipose tissue and thick-walled blood vessels were minimally identified. A small amount of extramedullary hematopoiesis was observed in the sinusoidal spaces between tumor cells. Tumor cells were diffusely immunoreactive for human melanoma black 45 (HMB45) and Melan A, focally immunoreactive for smooth muscle actin, but not for hepatocyte specific antigen (HSA).

Epithelioid angiomyolipoma of the liver: a case report

Epithelioid angiomyolipoma (EAML) of liver is a rare neoplasm. Hepatic EAML is often misdiagnosed as other neoplasms such as hepatocellular carcinoma due to non-specific clinical and radiologic features. The morphologic features under microscope and immunohistochemistry staining profile are important in the diagnosis EAML. Here, we report a case of 52-year-old man who found 1.2 cm mass in liver by routine checkup. On the impression of hepatocellular carcinoma, lateral sectionectomy of the liver was done. Microscopically, the tumor is composed of predominant epithelioid cells with vascular component and foamy cells. These cells were positive for HMB45, MelanA, and smooth muscle actin and negative for epithelial membrane antigen. The final diagnosis was hepatic EAML.

Perivascular Epithelioid Cell Tumor in the Stomach

Perivascular epithelioid cell tumors or PEComas can arise in any location in the body. However, a limited number of cases of gastric PEComa have been reported. We present two cases of gastric PEComas. The first case involved a 62-year-old woman who presented with a 4.2 cm gastric subepithelial mass in the prepyloric antrum, and the second case involved a 67-year-old man with a 5.0 cm mass slightly below the gastroesophageal junction. Microscopic examination revealed that both tumors were composed of perivascular epithelioid cells that were immunoreactive for melanocytic and smooth muscle markers. Prior to surgery, the clinical impression of both tumors was gastrointestinal stromal tumor (GIST), and the second case was erroneously diagnosed as GIST even after microscopic examination. Although gastric PEComa is a very rare neoplasm, it should be considered in the differential diagnosis of gastric submucosal lesions.

Solitary Pigmented Plexiform Neurofibroma in Lower Eyelid: A Case Report

PURPOSE: Solitary plexiform neurofibroma of the eyelid without neurofibromatosis is a rare disease. We report a case of solitary plexiform pigmented neurofibroma of the eyelid without neurofibromatosis. CASE SUMMARY: A 12-year-old male visited our clinic with a painless palpable subcutaneous mass on the right lower eyelid. He had a history of Batter syndrome and attention deficit hyperactivity disorder. On initial presentation, clinical features regarding neurofibromatosis such as Lisch nodule, optic nerve glioma, or high myopia were not observed. We performed excision and biopsy of the lower lid mass under general anesthesia. Macroscopically, the tumor was 4.0 × 1.5 × 1.5 cm in size with irregular nodules. Microscopically, the tumor consisted of multiple, variably sized tortous enlarged nerve fascicles with clusters of pigmented cells. Immunohistochemical results revealed expression of S-100 protein. Pigmented cells express both S-100 and melan-A proteins, while nonpigmented cells express S-100 protein only. The tumor was finally diagnosed as plexiform pigmented neurofibroma. Dermatological evaluation revealed no evidence of systemic neurofibromatosis. CONCLUSIONS: Plexiform neurofibroma should be considered in the differential diagnosis of an eyelid mass, even if the patient does not have a history or clinical features of neurofibromatosis. Plexiform neurofibroma can be successfully managed with surgical excision.

Clinicopathological Features and Immunohistochemical Alterations of Keratinocyte Proliferation, Melanocyte Density, Smooth Muscle Hyperplasia and Nerve Fiber Distribution in Becker's Nevus

BACKGROUND: Although Becker's nevus (BN) is a relatively common disease, the systematic studies of clinicopathological and immunohistochemical results are poorly reported. OBJECTIVE: To investigate the clinicopathological features and immunohistochemical alterations of keratinocyte proliferation, melanocyte density, smooth muscle hyperplasia and nerve fiber distribution in BN. METHODS: Clinical and pathological data were collected in 60 newly-diagnosed BN cases. Immunohistochemical stain of Ki-67, Melan-A, keratin 15, smooth muscle actin and protein gene product 9.5 was performed in 21 cases. RESULTS: The median diagnostic and onset age was 17 and 12 years, respectively. Skin lesions usually appeared on the upper trunk and upper limbs. The pathological features included the rete ridge elongation and fusion and basal hyperpigmentation. Epidermal Ki-67, Melan-A and keratin 15 expression and dermal nerve fiber length were significantly higher in lesional and perilesional skin than in normal skin (p<0.05~0.01), while smooth muscle actin expression was upregulated only in skin lesion (p<0.05). CONCLUSION: Although the clinical diagnosis of BN is often straightforward, histopathology is helpful to differentiate from other pigmentary disorders. The hyperproliferation of keratinocytes, melanocytes, arrector pili muscle and dermal nerve fibers could be involved in the pathogenesis of BN.

Sclerosing Perivascular Epithelioid Cell Tumor of the Lung: A Case Report with Cytologic Findings

Benign perivascular epithelioid cell tumor (PEComa) of the lung is a rare benign neoplasm, a sclerosing variant of which is even rarer. We present a case of 51-year-old man who was diagnosed with benign sclerosing PEComa by percutaneous fine needle aspiration cytology and biopsy. The aspirate revealed a few cell clusters composed of bland-looking polygonal or spindle cells with fine granular or clear cytoplasm. Occasional fine vessel-like structures with surrounding hyalinized materials were seen. The patient later underwent wedge resection of the lung. The histopathological study of the resected specimen revealed sheets of polygonal cells with clear vacuolated cytoplasm, variably sized thin blood vessels, and densely hyalinized stroma. In immunohistochemical studies, reactivity of tumor cells for human melanoma black 45 and Melan-A further supported the diagnosis of benign sclerosing PEComa. To the best of our knowledge, this is the first case of benign sclerosing PEComa described in lung.

Modulation of Melanin Synthesis by Amaranthus spp. L Seed Extract in Melan-a Cells

Anti-melanogenic effects of amaranth (AT), one of the key source of squalene, were investigated in melanocytes. Amaranth seed powder was extracted with water and melan-a cells were treated with various concentrations of AT. By using HPLC, content of myo-inositol, one of potential active components, was measured in the crude extract of AT.AT reduced the melanin content in melan-a melanocytes and down-regulated melanogenic enzyme activity such as tyrosinase, TRP-1 and TRP-2. By regulating melanogenic enzyme activity, AT may be a potential natural source for whitening agent. Myo-inositol was detected in AT by HPLC and may be one of the active compounds from AT involved in the regulation of anti-melanogenesis. In this study, we demonstrated that AT has anti-melanogenesis properties. This new function of amaranth may be useful in the development of new skin-whitening products and its value as food.

Expression of Epidermal c-Kit+ of Vitiligo Lesions Is Related to Responses to Excimer Laser

BACKGROUND: The survival and growth of melanocytes are controlled by the binding of stem cell factor to its cell surface receptor c-kit+ (CD117). We have observed that c-kit+ melanocytes existed in some lesions of vitiligo, while Melan A+ cells were absent. OBJECTIVE: To verify possible relation between c-kit+ expression and treatment response in non-segmental vitiligo lesions. METHODS: Skin biopsies were done from the center of the 47 lesions from the 47 patients with non-segmental vitiligo. Expression of c-kit+ and Melan A, and amounts of melanin in the epidermis were assessed in each lesion, and treatment responses to excimer laser were evaluated. RESULTS: Thirty-five of the 47 lesions (74.5%) had c-kit+ phenotypes. There was significant difference of c-kit staining value between good responders in 3 months of excimer laser treatment (average of 24 sessions) and the others. CONCLUSION: c-Kit expression in vitiliginous epidermis may be related to better treatment responses to excimer laser.

Tranexamic Acid Diminishes Laser-Induced Melanogenesis

BACKGROUND: The treatment of post-inflammatory hyperpigmentation (PIH) remains challenging. Tranexamic acid, a well-known anti-fibrinolytic drug, has recently demonstrated a curative effect towards melasma and ultraviolet-induced PIH in Asian countries. However, the precise mechanism of its inhibitory effect on melanogenesis is not fully understood. OBJECTIVE: In order to clarify the inhibitory effect of tranexamic acid on PIH, we investigated its effects on mouse melanocytes (i.e., melan-a cells) and human melanocytes. METHODS: Melan-a cells and human melanocytes were cultured with fractional CO2 laser-treated keratinocyte-conditioned media. Melanin content and tyrosinase activity were evaluated in cells treated with or without tranexamic acid. Protein levels of tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 were evaluated in melan-a cells. Signaling pathway molecules involved in melanogenesis in melanoma cells were also investigated. RESULTS: Tranexamic acid-treated melanocytes exhibited reduced melanin content and tyrosinase activity. Tranexamic acid also decreased tyrosinase, TRP-1, and TRP-2 protein levels. This inhibitory effect on melanogenesis was considered to be involved in extracellular signal-regulated kinase signaling pathways and subsequently microphthalmia-associated transcription factor degradation. CONCLUSION: Tranexamic acid may be an attractive candidate for the treatment of PIH.

Clinicopathologic Features of Progressive Macular Hypomelanosis in Korea / 대한피부과학회지

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.

Amelanotic corneally displaced malignant conjunctival melanoma: a case report evaluated with impression cytology / Melanoma amelanótico conjuntival maligno deslocado sobre a córnea com citologia de impressão: relato de caso

Here we describe the case of a 65-year-old Caucasian female who presented with an amelanotic malignant conjunctival melanoma and highlight the clinical and pathological features of this rare entity that displayed exclusive corneal invasive growth without evidence of conjunctival tumors other than primary acquired melanosis. Impression cytology aided in the initial diagnosis. The patient underwent surgical treatment. Histopathology and immunohistochemistry revealed an invasive amelanotic melanoma limited to the cornea and exhibiting S-100, Melan A, and HMB-45 positivity. The absence of pigmentation delayed early clinical detection and treatment. Awareness of this nonpigmented melanoma is important for early recognition and appropriate management.

Os autores descrevem o caso de uma mulher branca de 65 anos que apresentava um melanoma amelanótico maligno conjuntival e destacam as características clínicas e patológicas desta entidade rara com crescimento invasivo exclusivo na córnea sem evidência de tumores na conjuntiva além de melanose adquirida primária sem pigmento. A citologia de impressão auxiliou no diagnóstico inicial. A paciente foi submetida a tratamento cirúrgico. A histopatologia e a imuno-histoquímica revelaram um melanoma amelanótico invasivo limitado sobre a córnea exibindo positividade para proteína S-100, Melan A e HMB-45. A ausência de pigmentação retardou sua identificação clínica e seu tratamento precoce. O conhecimento deste melanoma não pigmentado é importante para o reconhecimento precoce e a conduta apropriada.

Immunohistochemical Double Staining of Ki-67/Melan-A in Melanocytic Nevi and Malignant Melanomas / 대한피부과학회지

BACKGROUND: Melanomas need to be differentiated from benign melanocytic lesions during diagnosis. However, it is difficult to differentiate them using histopathology alone, since both neoplasms have broad morphological spectrums and subtle differentiating features. OBJECTIVE: To evaluate the usefulness of Ki-67/Melan-A double staining for differentiating melanoma from benign melanocytic nevi. METHODS: We selected 20 cases of intradermal nevi, 20 cases of compound nevi, 5 cases of dysplastic nevi, and 25 cases of melanoma from clinicopathologically proven cases reviewed by the Department of Dermatology at our medical center. Ki-67/Melan-A double staining was performed, and the Melan-A verified Ki-67 index (Ki-67-M index) and Ki-67 index were measured. The immunopositivity was measured in the deepest third of the lesions. RESULTS: The Ki-67-M index of intradermal nevi, compound nevi, dysplastic nevi, and melanoma were 0.4+/-0.9%, 1.0+/-1.1%, 4.3+/-1.7%, and 24.1+/-10.9%, respectively. The best Ki-67/Melan-A cut-off point to distinguish melanomas from benign melanocytic nevi was 5%; the sensitivity and specificity were 100% and 97.7%, respectively. Immunopositivity in the deepest third of the intradermal nevi, compound nevi, and melanoma, were 10.5%, 20%, and 100%, respectively; the sensitivity and specificity for diagnosing melanoma were 100% and 84.6%, respectively. The sensitivity and specificity of combined Ki-67-M and immunopositivity in the deepest third for diagnosing melanoma were 100% and 97.7%, respectively. CONCLUSION: The Ki-67-M index and immunopositivity in the deepest third of melanoma were significantly higher than that of benign melanocytic nevi. Therefore, Ki-67/Melan-A double staining is a potentially valuable diagnostic tool for differentiating melanoma from benign melanocytic nevi.

Hepatic epithelioid angiomyolipoma: a clinicopathologic analysis of 25 cases / 中华病理学杂志

<p><b>OBJECTIVE</b>To study the clinicopathologic features, immunophenotype, histological diagnosis and prognosis of hepatic epithelioid angiomyolipoma.</p><p><b>METHODS</b>Clinical data of 25 cases of hepatic epithelioid angiomyolipoma were collected along with follow-up study of the patients. The pathological features were documented and immunohistochemical study of various markers was performed with an emphasis on diagnosis and differential diagnosis.</p><p><b>RESULTS</b>Hepatic epithelioid angiomyolipoma was more commonly found in young women without characteristic clinical symptoms. Its morphological features were characterized by marked cytological atypia, relatively rare mitotic figures; radial distribution of tumor cells around the thin-walled blood vessels or muscular vessels; and the presence of common multinucleated giant cells and large ganglion-like tumor cells. The tumor cells expressed both melanoma cell markers (HMB45, MART-1) and smooth muscle cell markers (SMA). Tumor cells expressed various other markers including ER 16% (4/25), PR 32% (8/25), TFE3 24% (6/25) and p53 60% (15/25).</p><p><b>CONCLUSIONS</b>Hepatic epithelioid angiomyolipoma has variable morphological features and characteristic immunohistochemical phenotype. The differential diagnoses include a variety of tumors. The biological behavior of the tumor tends to be benign.</p>

Resveratrol-Enriched Rice Down-Regulates Melanin Synthesis in UVB-Induced Guinea Pigs Epidermal Skin Tissue

Synthetic compounds that are used in the clinic to regulate skin hyperpigmentation, such as arbutin, hydroquinone, and kojic acid, are only moderately effective. But, their use is limited by side effects. As part of an effort to overcome the limitations, we developed resveratrol-enriched rice (RR) using genetic engineering technique. Each of resveratrol and rice has been reported to produce anti-melanogenic effects. Therefore, we hypothesized that RR would show more anti-melanogenic effects than those of resveratrol or rice alone. Anti-melanogenic effect of RR was done by using melan-a mouse melanocytes. The depigmenting efficacy was then observed following topical application of the RR to UVB-stimulated hyperpigmented dorsal skin of guinea pigs. Treatment with RR extract resulted a 21.4 +/- 0.7% decrease in tyrosinase expression at melan-a cells. Colorimetric analysis showed a significantly lower depigmenting value by day 9 following treatment with RR in UVB-irradiated guinea pigs the dorsal skin (p<0.01), indicating that RR produced a depigmentation effect. By staining with Fontana-Masson stain, we found that the RR-treated group had more effect histopathologically in epidermal melanin production than resveratrol or rice alone-treated group. RR was associated with reduction in the levels of microphthalmia-associated transcription factor (MITF), and downregulation of tyrosinase and tyrosinase-related protein (TRP-2) expression, leading to inhibit epidermal melanin production by western blot analysis. This study suggests that the resveratrol-enriched rice may be a promising candidate in regulating skin pigmentation with UVB exposure.