Idiopathic guttate hypomelanosis: an electron microscopy study

Idiopathic guttate hypomelanosis: Presentation and Management

Idiopathic guttate hypomelanosis (IGH) is a benign, typically asymptomatic, acquired leukoderma characteristically affecting mature individuals. Although the etiopathogenesis is unclear, chronic sun exposure and senile degeneration are important triggers. Researchers have been engaged in a continuous effort to unveil the gray areas encompassing different aspects of IGH pathogenesis. IGH is a clinical diagnosis; however, histopathology and dermoscopy may aid in quetionable cases. Patients often seek cosmetic treatment. There has been no standard therapy for this condition. Newer treatment modalities range from topical agents to procedure-based therapies and have enhanced the therapeutic armamentarium. Here we discuss the pathogenesis, presentation, and management of IGH.

Idiopathic Guttate Hypomelanosis Treated with 308-nm Excimer Light and Topical Bimatoprost

Idiopathic guttate hypomelanosis (IGH) is an acquired pigmentary disorder that is characterized by the presence of multiple hypopigmented macules on the shins and forearms. Albeit asymptomatic, it can cause considerable cosmetic anxiety. The pathogenesis is not fully understood and to date, there have been no successful treatments. We report a case of a 48-year-old female who presented with an 8-year history of multiple hypopigmented macules on both legs, typical of IGH. She previously failed to respond to topical pimecrolimus. She received targeted phototherapy with an excimer lamp (308 nm, 250–480 mJ), and a small patch was treated once daily with topical bimatoprost, in addition to the excimer lamp. After five sessions, better improvement was noted on the combination treatment patch; she received combination treatments for further six sessions. Good repigmentation has been achieved on the smaller macules. The larger depigmented macules continue to improve with further treatments. A combination of excimer light with topical bimatoprost appears to be a promising potential treatment option for IGH, a condition where management options are otherwise limited.

Do oxidative stress and melanin accumulation contribute to the pathogenesis of idiopathic guttate hypomelanosis: A prospective case-control study

BACKGROUND

Oxidative stress parameters have been reported to be significantly higher than controls in diverse disorders of pigmentation but no such data seem to be extant for IGH.

OBJECTIVES

To verify whether heightened oxidative stress levels are seen in patients with IGH (compared with matched controls) and quantify the same in blood using appropriate biochemical markers. Further, an attempt to determine if there might be any correlation between the amount of oxidative stress and the severity of the disease.

METHODOLOGY

This prospective case-control study was conducted in Northern India. Thirty Indian patients (Fitzpatrick skin phototype (SPT) IV-V) were included. The diagnosis of IGH lesions was confirmed based on characteristic clinical, and dermoscopic characteristics and confirmed on histopathological examination (H & E) of one of the lesions.

RESULTS

The oxidative stress enzyme level was significantly higher among the cases compared to controls which were statistically significant (p < 0.05). A positive correlation was also observed between the levels of these markers and number of lesions, but this finding was statistically not significant [p > 0.05]. Assessment of melanin level by Dopa staining method in the IGH lesions revealed irregularly distributed melanin with areas of high and low melanin content and greater accumulation in the basement layer.

CONCLUSION

The results of this probably the first study evaluating oxidative stress in IGH show that the oxidative stress is increased in patients with IGH. Level of oxidative stress seems to be correlated with both age of the patient (more in the elderly) and number of lesions.

Melanocyte abnormalities and senescence in the pathogenesis of idiopathic guttate hypomelanosis

BACKGROUND

Idiopathic guttate hypomelanosis (IGH) is a pigmentary disorder of unknown pathogenesis characterized by small discrete white macules. In the skin, epidermal melanin unit between melanocytes and keratinocytes is responsible for melanin synthesis and equal distribution of melanin pigment.

OBJECTIVE

Therefore, this study was designed to check the role of melanocytes in the pathogenesis of IGH.

METHODS

For this study, six IGH patients and six controls were enrolled. Melanin content was checked in the skin sections and in the cultured melanocytes. Senescence was checked in the lesional skin of IGH patients by comparing the mRNA and protein expression of senescence markers p16, hp1, and p21.

RESULTS

Cultured melanocytes from the IGH patients showed morphological changes in comparison to the control melanocytes. Melanocytes from IGH patients were bigger in size with very small and retracted dendrites as compared to the control melanocytes. Melanin accumulation was more in the IGH patients as compared to the controls. Our results showed that expression of p16, p21, and hp1 was significantly higher in lesional skin of IGH patient as compared to healthy controls.

CONCLUSION

This study revealed large-sized melanocytes with small and retracted dendrites in IGH patients. Accumulation of more melanin in the IGH melanocytes might be due to problem in the transfer of melanin from melanocytes to keratinocytes. Accumulation of melanin can lead to the senescence in the melanocytes of IGH patients.

Idiopathic Guttate Hypomelanosis: A Review of its Etiology, Pathogenesis, Findings, and Treatments

Idiopathic guttate hypomelanosis is a common acquired leukoderma characterized by multiple, discrete round or oval, porcelain-white macules on sun-exposed areas, especially on the extensor surface of forearms and pretibial areas. It usually affects individuals aged over 40 years and the likelihood of acquiring it increases with age. The exact pathogenesis remains controversial. However, there are several factors that are believed to be involved such as aging, ultraviolet exposure, trauma, genetic factors, autoimmunity, and local inhibition of melanogenesis. Despite the benign course of progression, many patients visit medical centers owing to cosmetic concerns and to confirm the natural course of idiopathic guttate hypomelanosis. Because there is no standard therapy for this condition, numerous medical and surgical treatments including intralesional corticosteroids, topical retinoids, topical calcineurin inhibitors, phenol peeling, cryotherapy, superficial dermabrasion, skin grafting, and ablative and non-ablative lasers have been tested with mixed results. This article will thoroughly review the etiology, pathogenesis, clinical presentations, histologic, dermoscopic, and ultrastructural findings, and the treatment of idiopathic guttate hypomelanosis.