Disorders of hyperpigmentation. Part I. Pathogenesis and clinical features of common pigmentary disorders

Disorders of hyperpigmentation are common and, depending on the extent and location of involvement, can affect the quality of life and pose a significant psychologic burden for patients. Given the similarities in presentation of the various causes of hyperpigmentation, it is often difficult to elucidate the etiology of these conditions, which is important to guide management. Furthermore, certain disorders, such as lichen planus pigmentosus and ashy dermatosis, have similar clinical and/or histologic presentations, and their classification as distinct entities has been debated upon, leading to additional confusion. In this review, the authors selected commonly encountered disorders of hyperpigmentation of the skin, subdivided into epidermal, dermal, or mixed epidermal-dermal disorders based on the location of pigment deposition, along with disorders of hyperpigmentation of the mucosa and nails. Melanocytic nevi, genetic disorders, and systemic causes of hyperpigmentation were largely excluded and considered to be outside the scope of this review. We discussed the pathogenesis of hyperpigmentation as well as the clinical and histologic features of these conditions, along with challenges encountered in their diagnosis and classification. The second article in this 2-part continuing medical education series focuses on the medical and procedural treatments of hyperpigmentation.

Penile melanosis with annular fibrillar pattern

Penile melanosis is an uncommon but benign condition. Its appearance, however, can cause significant distress to patients. We report a case of a patient presenting with hyperpigmented annular penile macules, with a fibrillar pattern seen on dermoscopy. Histopathological examination revealed basal keratinocyte hyperpigmentation with no melanocytic proliferation or atypia, confirming our diagnosis of penile melanosis. The patient was managed conservatively. We also reviewed the literature surrounding the clinical assessment and management of penile melanosis. Future reports on this topic with clinical-dermoscopic-pathological correlations will aid further understanding of this seldom reported condition.

Evaluation of large clinically atypical vulvar pigmentation with RCM: atypical melanosis or early melanoma?

BACKGROUND

Vulvar melanosis can occasionally be clinically challenging by mimicking an early melanoma.

OBJECTIVE

To report our experience of initial evaluation and follow-up in this peculiar subset of vulvar melanosis using reflectance confocal microscopy (RCM).

METHODS

We retrospectively evaluated 18 consecutive cases referred for atypical vulvar pigmentation or for which melanoma was considered and that underwent both RCM examination and histopathological assessment. In 13 cases with available dermoscopic pictures, RCM classification was compared to dermoscopic diagnosis, and in all cases, the density of melanocytes was evaluated on biopsies using MelanA immunostaining.

RESULTS

Among the 18 atypical pigmented lesions, 17 vulvar melanosis and one melanoma were histologically determined. RCM concluded a benign vulvar melanosis in 10 of 17 cases, whereas dermoscopy did so in three of 12 cases. RCM identified the only early malignant lentiginous melanoma. In several cases of vulvar melanosis, RCM could identify foci of melanocytic hyperplasia in an otherwise benign pattern.

CONCLUSIONS

In this clinically and dermoscopically challenging subset of vulvar pigmentations, RCM appears relevant for initial extensive evaluation, especially to target initial biopsy sampling, and to perform non-invasive monitoring of foci of melanocytic hyperplasia.

Noninvasive RCM for Differentiation of Melanotic Macules From Melanocytic Lesions-Blinded Evaluation of a Series of 42 Pigmented Macules

BACKGROUND

Differentiation of melanotic macules from melanocytic lesions, most importantly of melanoma, is a common problem on clinical-dermoscopic examination.

OBJECTIVE

To assess the value of noninvasive reflectance confocal microscopy (RCM) in the differential diagnosis of melanotic macules and melanocytic lesions.

PATIENTS AND METHODS

Reflectance confocal microscopy images of 42 pigmented macules on mucocutaneous junctions of genitalia and lips, including 31 melanotic macules, 6 nevi, and 5 melanomas, were retrospectively and independently assessed in a blinded manner by one expert observer and 2 less experienced observers together.

RESULTS

The authors differentiated 3 subtypes of melanotic macules; 2 subtypes ("solar lentigo type" and regular subtype of "dendritic type" melanotic macules) could be classified with confidence as benign by all RCM investigators, comprising 64% of melanotic macules. The third subtype (irregular subtype of "dendritic type" melanotic macules; 36%) displaying RCM features overlapping with melanoma was difficult to differentiate and should be biopsied not to miss a melanoma. The RCM differentiation between melanotic macules and nevi was easily performed.

CONCLUSION

RCM has the potential to increase the diagnostic accuracy in the noninvasive differentiation of pigmented macules on mucocutaneous junctions.

[Dermatological diseases of the external male genitalia : Part 1]

The urological examination of male patients includes an inspection of the external genitalia whereby a variety of dermatological alterations can be found. Not all dermatological findings are of clinical relevance. Pearly penile papules and heterotopic sebaceous glands are examples of normal physiological variations. Most penile melanotic macules, angiokeratomas, fibromas and angiomas do not have to be treated; however, penile skin lesions may also be symptoms of other diseases, such as circinate balanitis in Reiter's syndrome and multiple angiokeratomas in Fabry's disease. A typical manifestation of reactions to various drugs is the fixed drug eruption of penile skin. The differential diagnosis of various forms of balanoposthitis may be difficult and requires histological investigations (e.g. plasma cell balanitis or Zoon's disease). In contrast, the clinical manifestation of lichen sclerosus et atrophicus is easy to recognize. The clinical relevance of this disease is due to phimosis and problems during sexual intercourse.

A clinical, histologic, and follow-up study of genital melanosis in men and women

BACKGROUND

Genital melanosis may clinically mimic melanoma. Little is known about the potential risk for genital and nongenital melanoma in these patients.

OBJECTIVE

In this retrospective cohort study, we analyzed clinical and histologic data from patients with genital melanosis to better characterize these lesions and the risk they confer for genital and nongenital melanoma.

METHODS

In all, 41 patients were identified for a retrospective chart review and histologic analysis.

RESULTS

Genital melanosis can clinically mimic melanoma but the typical age of onset is younger than for genital melanoma. A majority of lesions were found to stabilize or regress over time. Five patients were found to have a history of melanoma, only 1 of which was in the genital region. Lesions from these patients were more likely to show melanocytes with suprabasal movement (P = .0101) and to have a higher melanocyte count (P < .0462).

LIMITATIONS

We present a relatively small cohort of patients with an average follow-up of only 30.5 months.

CONCLUSION

Patients with genital melanosis, and in particular those with any level of histologic atypia in the genital melanosis lesion, may require careful total body skin examinations for the possibility of melanoma in any body site.

Features of pigmented vulval lesions on dermoscopy

BACKGROUND

The dermoscopic criteria for benign and malignant lesions on the vulva are not well established due to the lack of large series of such lesions. Melanoma should always be included in the differential diagnosis of pigmented lesions on the vulva especially when they are wide, or of recent onset. Elsewhere on the skin dermoscopy plays an important role in the selection of suspicious pigmented lesions, as well as in the selection of the best site to perform the biopsy.

OBJECTIVES

To analyse the dermoscopic patterns observed in pigmented lesions of the vulva.

METHODS

We analysed a nonselected consecutive series of 68 histopathologically proven cases comprising five melanomas, 16 naevi, 20 lentigos, 12 benign vulval melanoses, 11 cases of postinflammatory pigmentation, three pigmented cases of usual vulval intraepithelial neoplasia (VIN) and one seborrhoeic keratosis seen at our institution. The dermoscope was covered by translucent disposable food wrap and/or antibacterial gel to prevent possible transmission of infections. Descriptive statistics were performed using multiple correspondence analysis.

RESULTS

The parallel (37%), ring-like (9%), homogeneous (22%), globular-like (13%) and reticular-like (6%) patterns were observed on benign lesions (naevi, lentigo, vulval melanosis and postinflammatory pigmentation). The cerebriform pattern (6%) was observed only on VIN and seborrhoeic keratosis. The multicomponent pattern (6%) was associated with melanoma (60%). In cases of melanoma we also occasionally observed an irregular pattern, a whitish or blue-whitish veil, irregularly distributed dots and globules and atypical vascular pattern. Using multiple correspondence analysis, we designed a new algorithm for the early detection of vulval melanomas.

CONCLUSIONS

Dermoscopy can play a role in the noninvasive classification of vulval melanosis. However, further studies of larger collaborative series are needed to validate our vulval melanoma diagnostic algorithm. VIN and seborrhoeic keratosis share the same dermoscopic features and biopsy should be considered for seborrhoeic-like keratosis. In case of doubt pathological examination of a biopsy remains mandatory.

[Atypical pigmented penile macules]

Two patients with pigmented lesions of the penis are described. The lesions consisted of asymptomatic, multifocal, irregular macules, with variegated pigmentation. The main differential diagnostic problem was with mucocutaneous melanoma. Histologic examination of the lesions showed basal layer hyperpigmentation. No cytologic atypia of melanocytes was detectable. The diagnosis in both cases was melanotic macules. Because of their atypical clinical appearance, genital melanotic macules are often misinterpreted as mucocutaneous melanoma. However histopathologic study solves the problem because genital melanotic macules show no melanocytic proliferation nor melanocytic atypia.

[Pigmented lesions of the genital mucosa]

Pigmented lesions of the genital mucosa are more frequent in women than in men. They represent a spectrum of different benign entities. A biopsy is always recommended when the diagnosis cannot be made with certainty on clinical examination and dermatoscopy. Differential diagnostic considerations include melanocytic nevi, blue nevi and syndromes featuring lentigines. Malignant melanomas of the penis and vulva are uncommon tumors which usually appear in elderly patients. They frequently present as painless palpable nodules at routine examination. The treatment consists of excision with histological control of the margins. An aggressive surgical approach has not been shown to prolong the poor 5-year survival. Cooperation with gynecologists and urologists is essential for the optimal management of such patients.

The Laugier-Hunziker syndrome

Laugier and Hunziker described a syndrome consisting of asymptomatic benign areas of hyperpigmentation affecting the lips, buccal mucosa and, in 50%, the fingernails. We report a 67-year-old woman with the clinical features of Laugier-Hunziker syndrome in association with vulval pigmentation. Histology, immunohistochemistry and electron microscopy from the various areas of pigmentation on the body confirmed the benign nature of the pigmentation. We review potential causes of oral and genital pigmentation, and suggest an expansion of the original syndrome described by Laugier and Hunziker to include more widespread areas of benign hyperpigmentation, which may associated.

Oral pigmentation

Oral pigmentation may be physiological or pathological in nature. It may represent a localized anomaly of limited significance or the presentation of potentially life-threatening multisystem disease. Evaluation of a patient with oral pigmentation requires a systematic approach with resource to appropriate investigations in certain circumstances. A full history of evolution of the pigmentary changes, as well as inquiring into family history, drug ingestion and systemic symptoms of concurrent disease are clearly important in the assessment. The duration, pattern, hue and distribution of colour changes can provide useful diagnostic clues. Special attention is given to newly appearing lesions, or those that have changed significantly in appearance, and biopsy may be needed to validate the clinical impression. This review should enable the reader to increase their familiarity with the assessment of oral pigmentation, the common causes of oral pigmentary change and the rarer disorders of pigmentation seen in this area. The systemic diseases that may give rise to oral pigmentation are detailed and the early signs of oral melanoma are highlighted, as well as the drugs which may cause pigmentary changes in this area and the different pattern of pigmentation they may induce.