Blue nevus of the oral cavity. An electron microscopic study

Plaque-Type Blue Nevus of the Oral Cavity

BACKGROUND

The blue nevus of the oral cavity is a rare lesion with important differential diagnoses. The plaque-type blue nevus is an uncommon variant of the blue nevus. Because of its particular clinical appearance, it can easily be confused with satellite metastases from malignant melanoma. The diagnosis usually requires a biopsy.

OBJECTIVES

To describe the clinical and histological features of a plaque-type blue nevus of the buccal mucosa in a 20-year-old white woman, to review all intraoral blue nevi and all plaque-type blue nevi reported in the literature so far and to compare the criteria of blue nevi and nevus of Ota.

RESULTS

An intraoral blue nevus was described for the first time in 1959. Since then around 70 further cases have been documented. Our case is the first report of a plaque-type blue nevus of the oral cavity.

CONCLUSIONS

The exceptional widespread intraoral blue nevus described herein can clinically be confused with an intraoral malignant melanoma, and it has a very similar clinical appearance as the intraoral part of nevus of Ota. Apart from the clinical resemblance, there is also some degree of histological overlap of the dermal melanocytoses. Transitional states between blue nevus and nevus of Ota may occur clinically and histologically.

The epithelioid blue nevus. A multicentric familial tumor with important associations, including cardiac myxoma and psammomatous melanotic schwannoma

We report on 21 pigmented nevi that occurred in 11 patients (6 male and 5 female patients) age 3 to 39 years. All patients had the Carney complex (myxomas, spotty skin pigmentation, endocrine overactivity, and schwannomas); six patients were members of three families. The nevi occurred on the extremities and trunk, less frequently on the head and neck, and were multiple in five patients. Clinically, they were darkly pigmented, domed, and small (less than 1 cm) and commonly interpreted as "blue nevi." Microscopically, they featured heavily pigmented, poorly circumscribed, dermal lesions that displayed two types of melanocytes: one intensely pigmented, globular, and fusiform; the other lightly pigmented, polygonal, and spindle. The melanocytes were situated among the dermal collagen bundles singly, in short rows and small groups, and occasionally in fascicles. Nuclei of the lightly pigmented, polygonal and spindle cells were vesicular with very pale chromatin and a single prominent nucleolus. Seven tumors were each part of a combined nevus. After excision, none of the tumors recurred or metastasized. The epithelioid blue nevus is important because of its strong association with the Carney complex. Therefore, affected patients (and their relatives) should be considered at risk for other elements of the syndrome, especially cardiac myxoma.

Blue-black macule on the maxillary palate

A cellular blue nevus located on the palate of a 72-year-old female is reported. This intraoral finding is uncommon and should be distinguished from clinical entities it closely resembles. Practitioners should be aware that a pigmented palatal lesion in fact may be a malignant melanoma. Surgical excision with microscopic examination is the only means by which an accurate diagnosis can be made.

S-100 protein content of dermal and oral mucosal blue nevi

Three common blue nevi from skin of the trunk and upper extremities, and 5 from oral mucosae were studied using an immunoperoxidase stain for S-100 protein. The skin lesions were uniformly negative whereas all of the oral mucosal lesions contained numerous positively stained dendritic cells. This difference may, in part, be explained by the different embryologic origins of the connective tissue stromas; the connective tissues of the head and neck are thought to be of neural crest origin whereas the connective tissues in the rest of the body are of mesodermal origin. These findings strengthen and refine the association between S-100 protein content and neural crest derivation.

The oral blue nevus: histogenetic implications of its ultrastructural features

Three cases of oral blue nevus are presented. A comparison of the ultrastructural features of blue nevus cells with those of schwannoma cells indicates that, among other similarities, both exhibit a surrounding external lamina (basement membrane). The significant difference is that blue nevus cells are capable of synthesizing melanin as evidenced by the presence of the entire melanosome maturation sequence within their cytoplasm, a feature not seen in the cells of schwannomas. This fundamental difference suggests that blue nevus cells are more closely related to melanocytes, although they possess some of the characteristics of Schwann cells.

Cellular blue nevus. An ultrastructural study

Cellular blue nevus can be clinically and histogenetically confused with malignant melanoma but remains a benign neoplasm of uncertain histogenesis. This paper reports the ultrastructural features of three cases of cellular blue nevus and emphasizes melanosomal alterations, including immature and granular forms, multiple layers of basement membrane around vessels, nerve fibers and tumor cells; endothelial fenestrations and banded structures within the nerve and outside in the stroma. A unifying concept of neural crest derived tumors is presented to better understand the histogenesis of cellular blue nevus.

Pigmented nevi of the oral mucosa: a clinicopathologic study of 32 new cases and review of 75 cases from the literature. Part II. Analysis of 107 cases

Review and analysis of data of seventy-five cases from the literature, together with an additional thirty-two new cases, revealed that nevi of the oral mucosa are not rare and may be more common than previously thought. Nevi of the intramucosal type are the most common, followed by the common blue nevus. Compound nevi are uncommon, and junctional nevi are very rare. The data are analyzed as to the location, presence of clinical pigmentation, configuration, size, and duration of the nevi, as well as the patient's age, sex, and race. Oral nevi (especially those that are clinically nonpigmented) are often misdiagnosed, indicating that they are far more common than they would seem from the reported cases. The potential for oral nevi to undergo malignant transformation is unclear because of the paucity of cases and limited follow-up. Nevertheless, we recommend that all oral pigmented nevi be removed.

Intraoral blue (Jadassohn-Tieche) nevus

Blue nevus of the oral mucosa is a distinctly uncommon clincial entity. Careful review of the literature yielded thirty-one previously reported cases. The present article reports the occurrence of a blue nevus of the hard palate in a 58-year-old man. It is of interest since it is the smallest (1 by 1 mm.) intraoral blue nevus to be reported. A clinicopathologic study of the previous thirty-one cases and of our case suggests that this lesion has no age or sex predilection. The most common site of occurrence was the hard palate. There appears to be no tendency toward recurrence. A brief review of the historical background, clinical features, theories of possible origin, and differential diagnosis is presented. Excisional biopsy of localized areas of oral pibmentation, together with histopathologic study, is indicated to rule out melanoma.

The ultrastructure of benign pigmented naevi and melanocarcinomas in man

Nine benign pigmented naevi and 16 melanocarcinomas (malignant melanomas) were studied by light and transmission electron microscopy and the fine structure of benign and malignant melanocytes is described. It was found that malignant melanocytes generally exhibit a range of abnormalities of structure of nuclei and cytoplasmic organelles which distinguish them clearly from their benign counterparts. Of the abnormalities, those affecting the specific organelle of the melanocyte, the melanosome, were the most constantly present. No firm evidence was found for the existence of two types of melanosome or two types of melanocarcinoma. Although electron microscopy is capable of showing in great detail within individual melanocytes many changes which are clearly associated with malignancy, the technique does not appear to offer significant advantages over light microscopy in determining the diagnosis and prognosis in this group of conditions.