Tinea versicolor: histologic and ultrastructural investigation of pigmentary changes

Characteristic Dermatoscopic Features of Hyperpigmented Macules on the Faces of Young Children

The aim was to describe the characteristic dermatoscopic features of hyperpigmented macules on the faces of young children. Sixteen patients with typical clinical presentations of hyperpigmented macules on the faces of young children were included in this study. The lesions were evaluated using a dermatoscope. The clinical and dermatoscopic features were analyzed and summarized. There were 12 boys and 4 girls enrolled in the study. The hyperpigmented macules had an age of onset ranging from 1 to 18 months (mean, 6.12 months). The hyperpigmentation was distributed on the forehead and/or temple, as follows: forehead (n = 8 [50%]); temple (n = 3 [18.8%]); and both sites (n = 5 [31.2%]). Fifteen patients (93.7%) had pseudoreticular pigmentation, 1 patient (6.3%) had reticular pigment with pseudoreticular pigment, and 100% had erythema and linear/branching vessels. Light brown pseudoreticular pigment and linear vessels were shown to be the 2 major dermatoscopic manifestations of hyperpigmented macules on the faces of young children.

Pityriasis Versicolor-A Narrative Review on the Diagnosis and Management

This narrative review presents a comprehensive overview of the diagnosis and management of pityriasis versicolor (PV), a common superficial fungal infection caused by the yeast Malassezia. PV is characterised by scaly hypopigmented or hyperpigmented patches, primarily affecting the upper trunk, neck, and upper arms. Regarding commensal interactions, Malassezia utilises nutrient sources without affecting the human host. In cases of pathogenicity, Malassezia can directly harm the host via virulence factors or toxins, or indirectly by triggering damaging host responses. The diagnosis typically relies on recognising characteristic clinical features. Due to the wide variability in its clinical presentation, recognising the differential diagnosis is critical. In this paper, we discuss the clinical differentials, with their dermatoscopic presentation, but also describe a range of helpful diagnostic techniques (microscopy, conventional and ultraviolet-induced fluorescence dermatoscopy, and confocal microscopy). Topical therapies are the primary treatment for PV, encompassing non-specific antifungal agents like sulphur with salicylic acid, selenium sulphide 2.5%, and zinc pyrithione. Additionally, specific topical antifungal medications with either fungicidal or fungistatic properties may also be incorporated into the topical treatment regimen, such as imidazoles, allylamines, and ciclopirox olamine. Systemic therapies might occasionally be used. Patient education and the promotion of good personal hygiene are pivotal to reduce the risk of recurrence. In recurrent cases, particularly during warmer and more humid periods, prolonged prophylaxis with topical agents should be considered.

Invisible dermatosis, diagnostic discrepancy between the general pathologist and dermatopathologist

BACKGROUND

Many clinically indicated skin biopsies show minimal histological changes referred to as "invisible dermatoses." They pose a challenge to general pathologists and dermatopathologists. This study determines the discrepancy between the general pathologists' diagnosis and the dermatopathologist's diagnosis and helps define a pathway for reaching the correct diagnosis.

METHODS

In total, 81 skin cases were selected from a tertiary hospital pathology department. They were diagnosed by general pathologists as "no specific diagnosis," or "minimal pathologic changes." These cases were reviewed carefully and diagnosed by a dermatopathologist. His diagnoses were compared with the original diagnoses.

RESULTS

Out of the 81 cases, 43 cases (53%) were reported by the dermatopathologist to have a specific diagnosis while 38 cases (46.9%) remained nonspecific. Both inflammatory and neoplastic diagnoses of potential clinical significance were made in the first group of 43 cases. The remaining 38 cases with nonspecific results were due to inadequate biopsy, inactive lesions or inadequate clinical data.

CONCLUSION

"Invisible dermatoses" describes skin diseases with clinically evident but histologically hidden changes. They are difficult cases for general pathologists and dermatopathologists to diagnose. Hence, it is important to be aware that minor changes on a skin biopsy do not mean it is disease-free.

Dermoscopic pattern of pityriasis versicolor

Background: Pityriasis versicolor (PV) is essentially a clinical diagnosis characterized by hypopigmented or hyperpigmented patches on the skin. Dermoscopy is gaining popularity as a noninvasive procedure for the diagnosis of different pigmentary and inflammatory disorders. However, scarce evidence exists on the dermoscopic pattern of PV. Objective: To describe the dermoscopic features of hypopigmented and hyperpigmented lesions of PV. Methods: Dermoscopic images of PV lesions located on different body sites were retrospectively evaluated for the presence of predefined criteria. Results: A total of 178 lesions from 125 patients were included in the study among which 164 lesions were hypopigmented and 14 lesions were hyperpigmented. Nonuniform pigmentation was the most common dermoscopic feature seen in both hypopigmented lesions (n=152, 92.68%) and hyperpigmented lesions (n=14, 100%). Scales were seen in 142 hypopigmented lesions (86.56%) and 13 hyperpigmented lesions (92.86%). Patchy scaling was more common in hypopigmented lesions (n=95, 57.92%) while scaling in the furrows was more common in the dermoscopy of hyperpigmented lesions (n=5, 35.71%). Inconspicuous ridges and furrows and perilesional hyperpigmentation were other significant features seen in dermoscopy of the lesions. Conclusion: To our knowledge, this is the first study describing the dermoscopic features of PV in such a large number of patients. Description of these new features adds valuable information and may help to establish dermoscopy as an important auxiliary tool for the diagnosis of PV.

Ultrastructural findings in progressive macular hypomelanosis indicate decreased melanin production

BACKGROUND

The pathogenesis of progressive macular hypomelanosis (PMH) is unknown. Recently, Westerhof et al. (Arch Dermatol 2004; 140: 210-214) hypothesized that Propionibacterium acnes produces a depigmenting factor that interferes with melanogenesis in the skin, resulting in hypopigmented spots. The purpose of the study is to gain an insight into the pathogenesis of PMH.

MATERIALS AND METHODS

We took a biopsy of 2-mm diameter from normal and lesional skin in eight PMH patients. Using electron microscopy, we compared melanization of melanosomes, melanosome transfer and amount of epidermal melanin in normal and lesional skin.

RESULT

Compared to non-lesional skin, we observed a decrease of epidermal melanin and less melanized melanosomes in lesional skin of all patients. When comparing normal and lesional skin of patients with skin type V and VI, we observed a difference in melanosome size and maturation and a switch of transferred melanosomes from single stage IV transferred melanosomes to aggregated stage I, II and III transferred melanosomes, as seen in healthy skin of skin type I to IV.

CONCLUSION

Hypopigmentation in PMH seems to be the result of an altered melanogenesis based on a decrease in melanin formation and a change in the distribution of melanosomes. In lesional skin of PMH patients with skin type V and VI less melanized, aggregated melanosomes in stead of single, mature melanosomes are transferred from melanocytes to keratinocytes. This results in a decrease of epidermal melanin. Further investigations are needed to determine the precise role of Propionibacterium acnes in this alteration of melanogenesis.

Recent developments in the immunology and biology ofMalasseziaspecies

Malassezia spp. are members of the normal cutaneous flora, but are also associated with several cutaneous diseases. Recent studies of the interaction of Malassezia spp. with melanocytes, fibroblasts, keratinocytes and dendritic cells have highlighted their potential to modulate the immune response directed against them. In normal skin they may downregulate the inflammatory response, allowing them to live as commensals. In contrast, in atopic/eczema dermatitis syndrome and psoriasis, they may elicit an inflammatory response that contributes to the maintenance of lesions. Future research may define ways to influence this inflammatory cycle and hence to control or prevent exacerbations of these diseases.

Pityriasis versicolor: a review of pharmacological treatment options

Pityriasis versicolor is a common disorder of the skin, which is characterised by scaly hypo- or hyperpigmented lesions on the body. The lipophilic yeast, Malassezia, is considered to be the aetiological agent of this disease. A number of treatment options, both topical and systemic, have been shown to be effective. A critical evaluation of treatment options is presented.

Malassezin, a novel agonist of the aryl hydrocarbon receptor from the yeast Malassezia furfur, induces apoptosis in primary human melanocytes

Pityriasis versicolor is the most common skin mycosis in humans worldwide. Yeasts of the genus Malassezia, particularly M. furfur, a saprophyte occurring widely on human skin, are generally regarded as the causative agents. Pityriasis versicolor is often accompanied by a long-lasting depigmentation that persists even after successful antimycotic therapy. M. furfur is able to convert tryptophan into a variety of indole alkaloids, some of them showing biological properties that correlate well with certain clinical features of pityriasis versicolor. This suggests a possible role for these compounds in the depigmentation process. We now report that human melanocytes undergo apoptosis when exposed to the crude mixture of tryptophan metabolites from M. furfur. The active compound was identified as malassezin, previously isolated by us from the same source and characterized as an agonist of the aryl hydrocarbon (Ah) receptor. The compound could, therefore, contribute to the marked depigmentation observed during the course of pityriasis versicolor.

Pityriasis versicolor alba

Pityriasis versicolor alba is a hypopigmented or depigmented variant of pityriasis versicolor characterized by maculous, partly pityriasiform, scaly depigmented lesions occurring particularly in seborrhoeic areas. Long-persisting hypopigmentation after healing of the pityriasis versicolor was first described by Gudden in 1853. Hypopigmentation and depigmentation were later differentiated as an independent variant of the disease. In 1848, Eichstedt recognized the pathogen-related character of pityriasis versicolor in its hyperpigmented form. Today it is generally accepted that the disease is caused by yeasts of the genus Malassezia, of which nine species are differentiated. It is controversial whether a single species is responsible for the disease. The pathogenesis of depigmentation has not been established. A screening effect by the scale layer as well as toxic effects on pigment synthesis by fungal metabolites have been discussed. With regard to the second mechanism, the newly discovered tryptophan-derived metabolites of M. furfur might be significant. Evidence-based data concerning the therapy of pityriasis versicolor alba do not exist. According to current recommendations, pityriasis versicolor should be rapidly treated with antimycotics, followed by ultraviolet therapy to induce maturation of existent melanosomes and accelerate repigmentation. However, depigmented lesions are difficult to improve by ultraviolet therapy.

Superficial fungal infections

Superficial fungal infections arise from a pathogen that is restricted to the stratum corneum, with little or no tissue reaction. In this Seminar, three types of infection will be covered: tinea versicolor, piedra, and tinea nigra. Tinea versicolor is common worldwide and is caused by Malassezia spp, which are human saprophytes that sometimes switch from yeast to pathogenic mycelial form. Malassezia furfur, Malassezia globosa, and Malassezia sympodialis are most closely linked to tinea versicolor. White and black piedra are both common in tropical regions of the world; white piedra is also endemic in temperate climates. Black piedra is caused by Piedraia hortae; white piedra is due to pathogenic species of the Trichosporon genus. Tinea nigra is also common in tropical areas and has been confused with melanoma.

Pityriasis versicolor

Pityriasis versicolor is a mild or chronic condition characterized by scaly hypopigmented or hyperpigmented lesions usually affecting the trunk. The lesions vary depending on tropical or temperate climates. The disease seems to occur mainly at adolescence when the sebaceous glands are more active. Malassezia yeasts have been implicated in the pathogenesis of this disease. The mycelial form of the fungus has been suggested to be the cause of lesions. Antifungal preparations have been used to treat the initial presentation effectively, although in a proportion of patients the disease tends to reoccur. They are available in a wide range of formulations and have been shown to be safe.

Pitiríase Versicolor

A expressão pitiríase versicolor define uma infecção fúngica superficial caracterizada por alterações na pigmentação cutânea. O distúrbio de pigmentação é devido à colonização do estrato córneo por um fungo dimórfico, lipofílico, encontrado na flora normal da pele, conhecido como Malassezia furfur. Trata-se de doença prevalente nos trópicos, mas também comum em climas temperados. Há vários tratamentos disponíveis com taxas elevadas de cura, porém as recorrências são freqüentes.

Pityriasis versicolor

Pityriasis versicolor is a common superficial fungal infection of the skin. It is caused by Malassezia spp., which are normal human saprophytes. Under certain conditions, both exogenous and endogenous, the fungus can convert from a yeast to a pathogenic mycelial form. This alteration results in mild inflammation of the skin, and in characteristic clinical and histological changes. The taxonomy of Malassezia spp. has recently been modified to include six obligatorily lipophilic species, all of which can be found on human skin, plus one non-obligatorily lipophilic species, which only rarely colonizes human hosts.

LEARNING OBJECTIVES

At the conclusion of this learning activity, participants should be aware of the role of Malassezia in the development of pityriasis versicolor, the clinical and histological changes arising from this dermatosis, and the diagnosis and treatment of this disorder.

Pigmentary changes of tinea versicolor in dark-skinned patients

BACKGROUND

Tinea versicolor causes scaly macular lesions which vary in color from white to brown. In patients with dark skin, tinea versicolor is thought to have a tendency to be hypopigmented. This view has not been formally documented.

OBJECTIVE

Our objective was to determine the pigmentary changes of lesions of tinea versicolor in patients with skin types IV and V.

METHODS

One hundred cases of tinea versicolor in persons with skin types IV and V were studied. The pigmentary changes and their correlation with the age and sex of the patients and the duration, recurrence, site, and symptomatology of the lesions were determined.

RESULTS

There was no correlation between the pigmentary variations of tinea versicolor and the type of skin, sex, and age of our patients or the duration, recurrence, site, and symptomatology of the lesions.

CONCLUSIONS

In dark-skinned individuals, tinea versicolor does not tend to be significantly hypopigmented.

Activating and dominant inactivating c-KIT catalytic domain mutations in distinct clinical forms of human mastocytosis

Human mastocytosis is characterized by increased mast cells. It usually occurs as a sporadic disease that is often transient and limited in children and persistent or progressive in adults. The c-KIT protooncogene encodes KIT, a tyrosine kinase that is the receptor for mast cell growth factor. Because mutated KIT can transform cells, we examined c-KIT in skin lesions of 22 patients with sporadic mastocytosis and 3 patients with familial mastocytosis. All patients with adult sporadic mastocytosis had somatic c-KIT mutations in codon 816 causing substitution of valine for aspartate and spontaneous activation of mast cell growth factor receptor (P = 0.0001). A subset of four pediatric onset cases with clinically unusual disease also had codon 816 activating mutations substituting valine, tyrosine, or phenylalanine for aspartate. Typical pediatric patients lacked 816 mutations, but limited sequencing showed three of six had a novel dominant inactivating mutation substituting lysine for glutamic acid in position 839, the site of a potential salt bridge that is highly conserved in receptor tyrosine kinases. No c-KIT mutations were found in the entire coding region of three patients with familial mastocytosis. We conclude that c-KIT somatic mutations substituting valine in position 816 of KIT are characteristic of sporadic adult mastocytosis and may cause this disease. Similar mutations causing activation of the mast cell growth factor receptor are found in children apparently at risk for extensive or persistent disease. In contrast, typical pediatric mastocytosis patients lack these mutations and may express inactivating c-KIT mutations. Familial mastocytosis, however, may occur in the absence of c-KIT coding mutations.

Vitiligo

Vitiligo involves a progressive loss of melanocytes from the epidermis and hair follicles. Milky-white patches appear resulting in cosmetic disfiguration that is most apparent in dark-skinned individuals. The disease is further classified according to distribution pattern and extent of depigmentation. The presence of several clinical subtypes may reflect the diversity in causative factors. To select appropriate therapeutic measures it is important to distinguish vitiligo from other disorders that affect melanocyte function. Although vitiligo has a characteristic clinical appearance and histological features, the presence of early or atypical lesions often requires the exclusion of other disorders such as postinflammatory hypopigmentation and piebaldism. Multiple hypotheses have been put forward to explain vitiligo. An inherited tendency to develop depigmentation may involve the inherent aberrancies that have been observed in nonlesional vitiligo melanocytes in vivo as well as in vitro. These abnormalities potentially render vitiliginous melanocytes more vulnerable to assaults from extracellular factors. Such factors include keratinocyte physiology, extracellular matrix composition, humoral and cellular immunity, and environmental agents. Therapies aimed at repopulation of lesional skin include phototherapy, application of topical corticosteroids, and transplantation of skin or skin cells. Moreover, micropigmentation or camouflage can be used to restore a pigmented appearance to lesional skin. In patients in which vitiligo affects extensive areas of the body, depigmentation may be the treatment of choice. In all, this acquired pigmentary disorder can be treated in a variety of ways and should not be regarded as an untreatable affliction.

The superficial mycoses

The various agents of the superficial mycoses have been recognized for more than a century as causes of mild diseases affecting humankind. Two of these, Malassezia furfur and Trichosporon beigelii, are ubiquitous organisms now known to be opportunistic pathogens in susceptible patient populations. The clinical manifestation, pathogenesis, and treatment of the common skin presentation of these and the other superficial mycoses are reviewed.