Use of DAPI cytofluorometric analysis of cellular DNA content to differentiate Spitz nevus from malignant melanoma

Cellular DNA content was measured for the purpose of differentiating Spitz nevus from malignant melanoma using the cytofluorometric technique. DNA was stained by 4',6-diamidino-2-phenylindole, and measured by microfluorometer. Among 20 Spitz nevi examined, 18 of them showed a diploid DNA distribution histographic pattern similar to that of acquired pigmented nevi. The other two Spitz nevi had a few polyploid cells with the major population of cells containing diploid DNA content. In contrast, all malignant melanomas showed an aneuploid DNA distribution histographic pattern. The DNA index values of cells from Spitz nevi distributed in the similar range to that of acquired pigmented nevi and separated from those of malignant melanomas distributed in a much higher range. Our results suggest that cytofluorometric analysis of cellular DNA content reflects the biologic behavior more sensitively than do conventional clinical or histologic criteria, and that it serves as a useful aid for the differentiation of Spitz nevus from malignant melanoma.     

Papular Epidermal Nevus with “Skyline” Basal Cell Layer (PENS) Following a Blaschko Linear Pattern

Papular epidermal nevus with “skyline” basal cell layer (PENS), a variant of epidermal nevi, has recently been described as a small, round or polygonal papule, visible at birth or shortly thereafter, with characteristic histopathologic features. It has been considered a separate entity from keratinocytic nevi because no lesion observed thus far has followed any of the known archetypical mosaic patterns. Here we describe for the first time a PENS lesion following a linear distribution pattern along Blaschko's lines.     

A comparative study of Spitz nevus and nodular malignant melanoma using image analysis cytometry

Image analysis cytometry can be used to estimate both nuclear DNA content and area in tissue sections. Since nodular malignant melanoma and Spitz nevus can show a remarkably similar light microscopic appearance, but may differ in behavior, we studied typical examples of these neoplasms to determine whether cytometric differences existed. Analysis of relative DNA content alone could not discriminate between these 2 entities in the 13 cases that we examined. However, Spitz nevi and nodular melanoma clearly differed in terms of maturation, which we defined as the difference between the mean nuclear size or mean nuclear DNA content of the uppermost and deepest melanocytes in each lesion. Maturation as defined by a decrease in mean nuclear DNA content proved highly significant (p less than 0.005). Only Spitz nevi showed a lesser DNA content in the deepest dermal cells as compared with upper dermal cells, suggesting that some Spitz nevi have an admixture of diploid and hyperdiploid cells in their upper portions, but mostly diploid cells in their deep portions. Only nodular melanoma showed higher mean DNA content in deep dermal cells as opposed to superficial dermal cells, suggesting that some nodular melanomas may either have clones of cells in their deep portions that have higher levels of ploidy, or more cells in the deep portion of melanomas may be in active phases of the cell cycle. Our study suggests that important cytometric differences exist between Spitz nevi and nodular melanoma, and that these could be exploited to develop cytometry into an adjunctive clinical technique.     

Familial papular epidermal nevus with “skyline” basal cell layer

Papular epidermal nevus with “skyline” basal cell layer is a variant of keratinocytic nevus that usually occurs sporadically but may affect different family members. We report on the fourth family with papular epidermal nevus with “skyline” basal cell layer affecting a 3‐month‐old girl and her father.     

A Case Report on the Dermoscopic Features of Spark's Nevus

Spark''s nevus is a compound word composed of Spitz nevus and Clark''s nevus. It is one of the combined melanocytic nevi which is more common in female and usually presents as a sharp circumscribed hyperpigmented macule on the lower extremities. On histopathologic findings, both cytologic features of Spitz nevus characterized as large spindle or epithelioid melanocytes containing large nuclei with abundant cytoplasm, and architecture of Clark''s nevus characterized as elongation of rete ridges, bridging of the nests, concentric and lamellar fibrosis can be seen. A 24-year-old female presented with an asymptomatic, solitary, dark-brown-colored papule surrounded by brownish patch that looked similar to dysplastic nevus or malignant melanoma on the buttock. On dermoscopic examination, it showed brown-to-black globules, diffuse homogenous pigmentation with blue-white structures, and a surrounding brownish reticular pattern that faded away. On histopathologic findings, overall asymmetrical structure, epithelioid large melanocytes containing large nuclei with abundant cytoplasm, and Kamino body were seen in the central portion. Also, lentiginous hyperplasia, bridging of the nests composed of melanocytes containing foamy cytoplasm, concentric and lamellar fibrosis along with the elongation of rete ridge, and perivascular lymphocytic infiltration were seen in the peripheral portion. The diagnosis of Spark''s nevus was made. Following its definition, this combined nevus is diagnosed histopathologically, but the clinicodermoscopic features have not been well described. Herein, we report a case of Spark''s nevus in which dermoscopy was helpful for differentiating it from malignant melanoma.     

Quantification of vascularity in nodular melanoma and Spitz's nevus

Spitz's nevi are acquired benign melanocytic skin tumors. Usually they are differentiated from nodular melanoma by clinical and histopathological criteria. Since Spitz's nevi are one of the most common simulators of nodular melanomas their bizarre histopathology may cause diagnostic confusion and make it difficult to differentiate these two melanocytic tumors. One of the histologic features shared by Spitz's nevus and nodular melanoma is prominent vascularity. The ability of malignant melanoma to induce angiogenesis is well established whereas benign melanocytic tumors do not have a prominent overall vascularity. The purpose of this study was to find out whether the degree of vascularity of nodular melanomas differs significantly from that of benign Spitz's nevi. In this study the number of microvessels and the vessel area were determined in 23 Spitz's nevi and 16 nodular melanomas. The number of microvessels and the vessel area were determined on Ulex Europacus agglutinin I-stained sections by computer-assisted image analysis. Two methods of measurement were used, namely systematic and selective sampling. Measurement of the whole tumor specimen (systematic sampling) revealed a vessel count of 10.83/field (SD±5.97) for Spitz's nevi whereas nodular melanomas exhibited a significantly lower (p=0.04) vessel count of 6.44/field (SD±3.85). This difference was even more pronounced when the vessel area (Spitz's nevi: 17.85×10–4mm², SD±10.32; nodular melanomas: 7.88×10-mm², SD×5.23) was investigated (p < 0.001). The difference in vessel area and vessel count was insignificant for areas exhibiting the greatest vascularity (selective sampling). Measurement of vessel count and vessel area lead us to conclude that Spitz's nevi have a significantly higher vascularity than do nodular melanomas. Our results thus indicate that angiogenesis in these pigmented lesions is not correlated with malignancy.     

Linear arrangement of multiple deep penetrating nevi: report of first case and review of literature

BACKGROUND: Deep penetrating nevus is a recently described variant of melanocytic nevi with clinical and histopathological features that may be confused with malignant melanoma, blue nevus, pigmented Spitz nevus, or congenital melanocytic nevus. We report a case with linear arrangement of multiple deep penetrating nevi. To our knowledge, such presentation has never been reported in the literature. OBSERVATIONS: We describe a patient with multiple darkly pigmented lesions in the right periauricular area, above and behind the ear. The histopathological features of these lesions were consistent with deep penetrating nevus. CONCLUSIONS: To our knowledge, this is the first report of linear arrangement of multiple deep penetrating nevi. We consider this case a unique presentation of deep penetrating nevus.     

Immunohistochemical characterization of Spitz's nevus: differentiation from common melanocytic nevus, dysplastic melanocytic nevus and malignant melanoma

Recently it has been reported that Spitz's nevus possesses a deranged melanogenesis with formation of the spherical melanosomes also seen in superficial spreading melanoma (SSM) and dysplastic melanocytic nevus (DMN). To characterize the nature of Spitz's nevus, immunohistochemical studies were carried out in 9 cases of this condition using monoclonal antibodies (MoAbs) which identify (a) human melanosome-associated antigen (HMSA-1 and HMSA-2), (b) S-100 protein (α and β subunits), (c) Leu-7 (HNK-1), (d) β2 microglobulin (B2MG), and (e) neuron specific enolase (NSE). In contrast to SSM and DMN, none of the 9 cases showed any significant reactivity with MoAbs HMSA-1 and HMSA-2. Similar to cutaneous malignant melanoma (CMM) and DMN, and unlike common melanocytic nevus (CMN), anti-S-100 protein α subunit MoAb reacted from moderately to intensely with Spitz's nevus, and anti-S-100 protein β subunit MoAb reacted weakly. Anti-B2MG MoAb was reactive with 8 of 9 cases. Only one case showed cytoplasmic reactivity to anti-Leu-7 MoAb. Polyclonal NSE was found in 7 cases at varying intensities. Our immunohistochemical study indicates the distinct, benign neoplastic nature of Spitz's nevus which has immunoreactivities differing from those of CMM, DMN and CMN.     

Angiomatoid Spitz nevus: a distinct variant of desmoplastic Spitz nevus with prominent vasculature

Five cases of a distinctive variant of desmoplastic Spitz nevus are reported. To the best of our knowledge, this tumor has never been described previously. Clinically, it presents itself as a solitary papule on the extremities of young adults. Microscopically, it shows predominance of solitary melanocytes with epithelioid appearance over cell nests. They are embedded in a prominent fibrous stroma with many densely arranged, small blood vessels with plump endothelia not seen in other Spitz nevi. Because of its resemblance to a vascular tumor, the name angiomatoid Spitz nevus is proposed for this lesion. Absence of recurrences or metastases after complete excision in all cases supports the benign nature of the tumor.     

Successful differentiation of Spitz naevus from malignant melanoma by microfluorometric analysis of cellular DNA content

Two cases of presumed Spitz naevus, whose diagnosis on clinical and histological grounds was uncertain, were examined for cellular DNA content using the technique of DAPI-DNA microfluoromety. They were compared with 20 cases, respectively, of clinically and histologically confirmed, Spitz, naevus, malignant melanoma and acquired pigmented naevus. The two Spitz naevi showed a diploid pattern in a distribution histogram of cellular DNA content. The pattern was similar to that of confirmed Spitz naevi and of acquired pigmented naevi but different from the aneuploid pattern of malignant melanomas. DNA index values of the two cases were within the range of confirmed Spitz naevi and different from those of malignant melanomas. The DAPI-DNA microfluorometric method thus provided confirmatory evidence for the diagnosis of Spitz naevus. The method appears to reflect sensitively the biological behaviour of tumour cells, and is a useful aid to the diagnosis of uncertain Spitz naevi.     

Hyalinizing Spitz nevus

A seventeen-year-old Korean girl had a reddish-brown papular lesion on the nose. Histopathologically, it proved to be a "hyalinizing Spitz nevus" with the characteristic features of a discohesive growth pattern of nevus cells and hyalinized stroma. Immunohistochemical stains showed positive reactivity of nevus cells with S-100 protein and Vimentin and negative stainings with HMB45, CD68, CEA and low molecular weight cytokeratin. Hyalinizing Spitz nevus may represent a variant in the spectrum of Spitz nevus.     

BAP1‐deficient and VE1‐negative atypical Spitz tumor

Atypical Spitz tumor with loss of BAP1 or Wiesner nevus is a peculiar variant of intradermal spitzoid melanocytic neoplasm composed of epithelioid melanocytes with a sheet‐like growth pattern, abundant infiltrating lymphocytes and rare or absent mitotic activity. This subset of atypical spitzoid tumors is characterized by the BRAF^V600E mutation and loss of BAP1 expression. Recognition of these lesions is important because they can be a marker for a hereditary BAP1‐associated cancer syndrome. We present an unusual case of sporadic Wiesner nevus that had typical histopathologic features and a BAP1 but not a BRAF mutation. The biological significance of Wiesner nevus is controversial, and little is known about prognosis, particularly in atypical cases like this one.     

Papular Epidermal Nevus with “Skyline” Basal Cell Layer (PENS) with Extracutaneous Findings

Abstract: Papular epidermal nevus with “skyline” basal cell layer (PENS), a variant of epidermal nevus, was recently described in otherwise normal children. We describe herein a patient with multiple, typical PENS lesions associated with peculiar facies, bilateral Achilles tendon shortening, and mild psychomotor delay. The association of PENS with extracutaneous manifestations suggests the possibility of a new type of epidermal nevus syndrome, for which we propose the term PENS syndrome.     

Plexiform spitz nevus: an intradermal spitz nevus with plexiform growth pattern

Two cases of a distinctive variant of Spitz (spindle and epithelioid cell) nevus are described. One lesion developed on the lower leg of a 17-year-old boy and the other lesion on the back of a 52-year-old man. The microscopic appearance was characterized by a plexiform arrangement of bundles and lobules of enlarged spindle to epithelioid melanocytes throughout the superficial and deep dermis. Intraepidermal melanocytic proliferation was unappreciated. Some lobules were circumscribed by a thin rim of compressed fibrous tissue. In both cases a myxoid stroma was present. The cells had abundant eosinophilic cytoplasm with well-defined borders. The nuclei were enlarged, consistently ovoid and vesicular, with small nucleoli. Both cases contained scattered multinucleate giant cells similar to those observed in classical form of Spitz nevi. No melanin pigment was detectable by light microscopy. No mitoses were observed in one case and a rare mitosis was present in the other. Tumor cells were strongly immunoreactive for S-100, but not for HMB-45, desmin, and actin. The differential diagnosis of this distinctive tumor includes desmoplastic/neurotropic melanoma, plexiform spindle cell nevus, cellular blue nevus, plexiform neurofibroma, and cellular neurothekeoma. The designation of "plexiform Spitz nevus" is chosen to emphasize its distinctive plexiform growth pattern.     

Familial papular epidermal nevus with “skyline” basal cell layer and multiple pilomatricomas: A new association?

Papular epidermal nevus with “skyline” basal cell layer is a newly described keratinocytic nevus. Recently, papular epidermal nevus with “skyline” basal cell layer has been reported in association with extracutaneous involvement, and the term papular epidermal nevus with “skyline” basal cell layer syndrome is used to indicate a neurocutaneous syndrome characterized by the presence of papular epidermal nevus with “skyline” basal cell layer and different neurologic symptoms that seem to improve during infancy and adolescence. Multiple pilomatricomas have been reported in association with various syndromes. We report herein papular epidermal nevus with “skyline” basal cell layer associated with multiple pilomatricomas in two members of a family with the aim of drawing attention to this peculiar epidermal nevus to improve our knowledge of the syndrome.     

Pseudogranulomatous Spitz nevus: a variant of Spitz nevus with heavy inflammatory infiltrate mimicking a granulomatous dermatitis

Spitz nevus is a benign melanocytic proliferation that shows relatively characteristic clinicopathologic features. Despite this, Spitz nevus is clinically confused with many other lesions, and histopathologically it is sometimes difficult to distinguish it from melanoma. However, Spitz nevus rarely causes differential diagnostic problems with granulomatous dermatitis. This article describes an 8‐year‐old girl who presented with a nodule on her right arm, a clinical appearance of a pyogenic granuloma. Histopathologically, there was a dermal lesion composed of aggregates of large epithelioid cells surrounded by a heavy inflammatory infiltrate, mimicking a sarcoid‐like granulomatous dermatitis. Immunohistochemistry showed epithelioid cells with strong nuclear and cytoplasmic staining with S‐100 protein, thus establishing the diagnosis of a melanocytic tumor. The heavy T‐cell lymphocytic infiltrate that accompanies the large epithelioid cells caused its granulomatous appearance. Molecular assessment showed H27H mutation in the HRAS gene. We suggest the term ‘pseudogranulomatous’ for this variant of Spitz nevus because it indicates that the lesion is not authentically granulomatous and simply mimics a granulomatous dermatitis.     

Recurrent nodules in a periauricular plaque‐type blue nevus with fatal outcome

Plaque‐type blue nevus is a rare variant of blue nevus characterized by grouped nodules displaying histomorphological features of a cellular blue nevus. We report the clinical, histopathologic and immunohistologic features of a patient with recurrent nodules in a periauricular plaque‐type blue nevus with malignant transformation and fatal outcome. The nevus was characterized clinically by childhood onset, with slow enlargement during adolescence. At age 16, the patient presented with nodules located retroauricularly. Several surgical excisions with the intent of complete removal of the nodules and the nevus were performed. Histopathological, dermal and subcutaneous proliferations of pigmented melanocytes with melanophages were detected. The nodules showed some cellular atypia and few mitotic figures, (Ki67 estimated <1%). At age 20, the patient developed new nodules retroauricular, with histopathology similar to previous lesions; however, the proliferation rate was higher. A comparative genomic hybridization (CGH) showed chromosomal changes indicative of melanoma. At age 25, the patient developed multiple liver metastases and died after 4 weeks. A sequencing of the tumor DNA revealed a GNAQ Q209P mutation, whereas mutations of GNA11, BRAF, NRAS and cKIT were not detected. This case shows that nodules in plaque‐type blue nevus may have malignant potential which may be uncovered by CGH.     

Hypopigmented Reed nevus

Reed nevus, also named pigmented spindle cell nevus, is a peculiar melanocytic nevus, now regarded as a variant of Spitz nevus by the majority of authors. It is characterized by spindle-shaped melanocytes disposed in nests located in epidermis and papillary dermis. It is usually heavily pigmented, and many melanophages may also be present. Hypopigmented Reed nevus shows all the typical features of conventional pigmented spindle cell nevus, but it does not contain abundant melanin. This variant of Reed nevus is poorly described in literature, so we report five cases of hypopigmented Reed nevus and discuss its clinical and histopathological features.