Chemical and Pharmacologic Agents that Cause Hyperpigmentation or Hypopigmentation of the Skin

Effects of Fluoride Exposure on Primary Human Melanocytes from Dark and Light Skin

Fluoride exposure has adverse effects on human health that have been studied in vitro in cell culture systems. Melanocytes are the melanin pigment-producing cells that have a significant role in the regulation of the process of melanogenesis, which provides several health benefits. Melanocytes are present in the oral cavity, skin, brain, lungs, hair, and eyes. However, to date, there has been no study on the effects of fluoride exposure on melanocytes. Hence, in the current study, we have studied the effects of sodium fluoride (NaF) exposure on neonatal human epidermal melanocytes (HEMn) derived from two different skin phototypes, lightly pigmented (LP) and darkly pigmented (DP). We have assessed the impact of a 24 h and 72 h NaF exposure on metabolic activity and membrane integrity of these cells. In addition, we have evaluated whether NaF exposure might have any impact on the physiological functions of melanocytes associated with the production of melanin, which is regulated by activity of the enzyme tyrosinase. We have also assessed if NaF exposure might induce any oxidative stress in LP and DP melanocytes, by evaluation of production of reactive oxygen species (ROS) and measurement of mitochondrial membrane potential (MMP) levels. Our results showed that HEMn-LP cells showed a higher sensitivity to NaF cytotoxicity than HEMn-DP cells, with significant cytotoxicity at concentrations >1 mM, while concentration range 0.25–1 mM were nontoxic and did not lead to oxidative stress, and also did not alter the levels of intracellular melanin or cellular tyrosinase activity, indicating that treatment up to 1 mM NaF is generally safe to melanocytes from both pigmentation phototypes.

Origin, clinical presentation, and diagnosis of hypomelanotic skin disorders

Hypomelanotic skin disorders are cutaneous pigmentary disorders characterized by a reduced melanin content in the skin that results in a lightening of the skin. Establishing the correct diagnosis for hypomelanotic skin disorders requires a good history, a detailed physical examination, the use of special lighting techniques, such as Wood's light, and sometimes a biopsy of the abnormally pigmented skin and the normally pigmented skin. This article focuses on the origin, clinical presentation, and diagnosis of acquired hypomelanotic skin disorders. An algorithm for the diagnostic approach to these hypomelanoses is given.

Photodistributed blue-gray pigmentation of the skin associated with long-term imipramine use

A 72-year-old white woman presented with progressively increasing slate-gray pigmentation of the face and extensor aspect of the forearms, which she had been suffering from for 8 years. She had been taking imipramine for approximately 30 years. Her other medications included ranitidine and anacin. Physical examination revealed slate-gray hyperpigmentation of the skin photodistributed on the face (Figs 1, 2) and extensor aspects of the forearms. Relative sparing of the skin folds, mucous membranes, sclerae, teeth, and nails was noted. The remainder of the physical examination revealed no abnormalities. Skin biopsy specimens from the right cheek and right forearm were obtained. Histologic examination revealed collections of variably sized, round to ovoid, yellow-brown globular deposits in the upper and mid dermis (Fig. 2). The deposits were identified within macrophages and free within the dermis. The epidermis was unremarkable and free of deposits. The deposits stained for melanin with a Fontana-Masson stain, but did not stain for iron.

Oral mucosal hyperpigmentation secondary to antimalarial drug therapy

A case of oral mucosal hyperpigmentation resulting from antimalarial drug therapy is presented. The patient reported a history of long-term quinacrine therapy and exhibited diffuse blue-gray pigmentation of the nail beds and the skin of the nasal ala. Microscopic examination of the involved mucosa showed macrophages, containing both melanin and ferric iron, scattered within the connective tissue adjacent to the epithelium. The clinical, historical, and microscopic features of antimalarial-induced pigmentation are discussed. Other causes of diffuse or multifocal oral pigmentation are also addressed.

Photoinduced dermal pigmentation in patients taking tricyclic antidepressants: histology, electron microscopy, and energy dispersive spectroscopy

Two patients had been taking long-term tricyclic antidepressant therapy. Each developed a blue to slate-gray hyperpigmentation in sun-exposed areas. On histologic examination there were refractile golden brown granules free in the dermis along collagen bundles. Similar pigment was present in macrophages and along the basement membrane zone. The granules stained for melanin, but not for iron, and were bleached by the permanganate method. Electron microscopy showed varying size and shaped electron-dense granules within lysosomes and free in the dermis, which, in unstained sections, showed a less dense peripheral halo. This peripheral halo was also evident on light microscopy. Energy dispersive spectroscopy showed these granules to be rich in copper and sulfur (elements present in tyrosinase and pheomelanin, respectively). We believe that this represents a drug-melanosome complex, which is most likely caused by chronic photoactivation.

Efficacy of topical treatment of pigmentation skin disorders with plant hydroquinone glucosides as assessed by quantitative color analysis

Hydroquinone is a well known reagent used in the treatment of pigmentation disorders. The instability of the quinones and the required active concentration make topical treatment rather difficult. We tested the efficacy of an ascorbate-phytohydroquinone complex that inhibits the synthesis of melanin and promotes the degradation of the existing melanin. Lentigo senile lesions were evaluated before and after 1 month of treatment. Objective skin color evaluation was performed instrumentally. After one month of treatment, a clear depigmentation of the macules was measured. None of the volunteers reported any side effects from the prolonged treatment with the hydroquinone containing product.

Oral lesions of iatrogenic and undefined etiology and neurologic disorders associated with HIV infection

A review of a miscellaneous group of oral mucosal disorders in the setting of infection with the human immunodeficiency virus is presented. Included is a discussion of oral lesions of iatrogenic and undefined etiology and neurologic disorders. Mechanisms of pathogenesis, including possible common pathways and relationships to underlying immunosuppression, are emphasized.