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.     

Desmoplastic hairless hypopigmented nevus (DHHN). A distinct variant of giant melanocytic nevus

Desmoplastic hairless hypopigmented nevus (DHHN) is the name Ruiz-Maldonado et al. gave to a new variant of giant congenital melanocytic nevus characterized clinically by a hard ligneous consistency, absence of hair and progressive loss of pigment. Histologically, dermal fibrosis consistent with desmoplasia is a predominant feature. We describe a 6-year-old boy with a hard hairless pigmented congenital nevus involving the lumbosacral area, buttocks, perineum and scrotum. During the first years of life, the nevus showed a progressive reduction in colour, size and consistency. These changes continued until the age of four when a well-demarcated tumour appeared, within the nevus, on the right buttock. Resection of this outgrowth was performed. Histologically, nevus cells of normal appearance between thick collagen bundles were present. Immunostaining revealed S100 +, Vim +, HMB45--results. The nevus has continued to involute to date. An immune response against the melanocytes of the nevus may explain this type of evolution.     

Desmoplastic sebaceoma arising from nevus sebaceus: a new variant

Nevus sebaceus is known to have the potential to develop into various secondary tumors. We observed a sebaceoma arising from a nevus sebaceus excised from the left cheek of a 51‐year‐old woman. This sebaceoma showed desmoplastic change similar to that observed in desmoplastic trichoepithelioma and desmoplastic trichilemmoma. This heretofore undescribed desmoplastic variant of sebaceoma should not be mistaken for invasive sebaceous carcinoma.     

Amelanotic blue nevus: a variant of blue nevus.

Blue nevi are typically heavily melanized. We report a variant of blue nevus that is minimally pigmented. Of the 1,358 blue nevi seen in our laboratory during the last 6 years, 38 (2.7%) were selected that had scant or absent melanin. We refer to these blue nevi as the amelanotic type. Approximately half of the cases in clinical diagnosis were nevus of some type, whereas other differential diagnoses were basal cell carcinoma, dermatofibroma, and lesion. Histologically all specimens were characterized by the spindle-shaped cells seen in blue nevi, but with very little or no obvious melanin. Some lesions were markedly cellular, resembling the features of cellular blue nevus. No hemosiderin was identified on Perls' stain, whereas Fontana-Masson stain was variably positive. Usually there was fibrous stroma. In most cases, the histologic differential diagnosis was dermatofibroma. Other histologic differential diagnoses included amelanotic and/or spindle cell melanoma, dermal Spitz nevus, neurofibroma, and scar. There was no pleomorphism or increased mitotic activity. Evidence of epidermal melanocytic hyperplasia was seen in two cases. Furthermore, the lesions had been present for many years without evidence of recent change. Immunohistochemistry showed all cases to be strongly positive with anti Mel-5 antibody, but only weakly positive or negative with anti S-100 and HMB-45 antibodies. We would like dermatologists and pathologists to be aware of this unusual and uncommon entity.     

Desmoplastic trichoepithelioma and intradermal nevus: a combined malformation

We studied 13 desmoplastic trichoepitheliomas associated with intradermal nevi. Ten intradermal nevi were found among 76 new cases of desmoplastic trichoepithelioma (13%); three additional examples of the combined malformation were seen in consultation. Clinically, desmoplastic trichoepithelioma associated with an intradermal nevus was typically a small, firm or hard, sometimes annular, nodule on the face, particularly the cheek, of a relatively young woman. Microscopically, the combined malformation contained narrow strands of basaloid cells and keratinous cysts in a desmoplastic stroma, intimately mixed with intradermal nests of nevocytes. Melanocytic nevi have been associated with epidermal hyperplasia resembling seborrheic keratoses, follicular cysts, trichostasis spinulosa, syringomas, basal cell carcinomas, and hair follicle formation on the soles. The frequency of the occurrence of intradermal nevus with desmoplastic trichoepithelioma and the close anatomic association of the two elements may indicate that this combined malformation is another example of epithelial induction by melanocytic nevi.     

Intraoral cellular blue nevus: report of a unique histopathologic entity and review of the literature

The blue nevus is found most frequently on the skin; however, in rare instances, it has been reported on oral mucous membranes. Intramucosal nevi make up more than one half of all reported intraoral melanocytic nevi. The common blue nevus is the second most common variant. Among the 3 variants of blue nevi, the cellular variant occurs less frequently than the common and combined variants. We present a rare case of intraoral cellular blue nevus that occurred on the oral mucosa of the hard palate. Because of the clinical and microscopic resemblance of the cellular blue nevus to melanoma and the rarity of this lesion in the oral cavity, recognition and accurate diagnosis are critical.     

Epidermal nevus syndrome associated with adnexal tumors, spitz nevus, and hypophosphatemic vitamin D-resistant rickets

The epidermal nevus syndrome is the association of epidermal nevi with abnormalities in other organ systems, most commonly the central nervous system, the skeletal system, and the eyes. We present a patient with epidermal nevus syndrome associated with hypophosphatemic vitamin D-resistant rickets and multiple adnexal and spindle cell tumors.     

Comparative dermatology: blue nevus

There are elements in nature that may be compared to some dermatological lesions, such as the black pearl, which is very similar to a cellular blue nevus observed in the gluteus region of a 31-year-old male patient.     

Cerebriform nevus sebaceus: a rare entity

We present a case of cerebriform nevus sebaceus in an 18-year-old boy. This form of nevus sebaceus is quite rare, in contrast to the relatively common linear variant.     

Linear Cowden nevus: a new distinct epidermal nevus

Within the group of epidermal nevi, a so far nameless disorder is described under the term "linear Cowden nevus". This non-organoid epidermal nevus is caused by loss of heterozygosity, occurring at an early developmental stage in an embryo with a germline PTEN mutation, giving rise to Cowden disease. Hence, linear Cowden nevus can be categorized as a characteristic feature of type 2 segmental Cowden disease. Until now, several authors had mistaken this epidermal nevus as a manifestation of Proteus syndrome. The concept of linear Cowden nevus implies that Proteus syndrome is by no means caused by PTEN mutations. As a clinical difference, linear Cowden nevus is markedly papillomatous and thick, whereas linear Proteus nevus tends to be rather flat. Moreover, the spectrum of possibly associated cutaneous or extracutaneous anomalies differs in the two types of nevi. In conclusion, linear Cowden nevus, that may also be called "linear PTEN nevus", represents a distinct clinicogenetic entity.     

皮内痣伴结缔组织增生性结节一例

患者男,28岁,因左侧胸部单发褐色肿物4年、多发小丘疹1年就诊。皮肤科检查：胸部左侧一1.2 cm × 1.1 cm × 1.0 cm褐色类圆形肿物,质韧,其右侧数个直径3 ~ 5 mm褐色丘疹,左侧腋下淋巴结未触及肿大。手术完整切除肿物后行组织病理检查：肿物和小丘疹内均可见真皮浅层痣细胞聚集成巢,考虑皮内痣;最大肿物...     

Spitz痣和恶性黑素瘤浸润细胞的免疫细胞化学研究

用多种单克隆抗体,借助间接免疫过氧化物酶技术对1例Spitz痣和2例恶性黑素瘤(MM)Ⅱ, Ⅲ期的皮损进行了观察.结果见在Spitz痣与MM的炎性细胞浸润中,T淋巴细胞(OKT11⁺)占相当比例.在Spitz痣中,T_H/T_S(Leu3a⁺Leu2a⁺)的值与正常人皮肤中的比值相近,而MM的T_H/T_S比值降低.在Ⅳ期MM中,见炎性细胞减少的同时T淋巴细胞的比例下降,并且单核细胞(Monol⁺)数量较多,OKT6⁺细胞缺如.上述结果说明,Spitz痣与MM的炎性浸润细胞在免疫组织化学表现型方面有一定差别,并提示了在MM中细胞免疫功能的异常.     

Characteristics of spitzoid melanoma and clues for differential diagnosis with spitz nevus

ABSTRACT:: The different features of spitzoid melanoma are not well characterized in the literature, and the lesion often has to be described in comparison with Spitz nevus. We evaluated the histopathological appearance of spitzoid melanoma by reviewing all spitzoid melanomas treated at our hospital and all referrals from 1998 to 2010. The final study sample comprised 18 cases, 11 from our institution and 7 referrals from other centers. We recorded clinical parameters (eg, age, sex, site, time between onset and excision, recurrence, and death) and a series of histopathological parameters (eg, size, ulceration, symmetry, Clark level, Breslow thickness, cell density, atypia, mitosis). Clinical and histopathological criteria were not available for the 7 referrals. Mean age was 35.2 years (15-56), and 8 patients were women. Mean size of the lesions was 7.27 mm (Clark III/IV and Breslow 2.51 mm), and these were found on the limbs and trunk. Cell density was high in 10 cases and atypia present in 9 (marked in 1). Mitoses were observed in 8 cases (atypical in 4, clusters in 4). Maturation was absent in 9 cases and zonation in 8. Our analysis revealed 5 previously undefined subtypes of spitzoid melanoma (genuine (7 cases), uniform (5 cases), packed (5 cases), polypoid (3 cases) and pigmented (2 cases)]. Four cases showed 2 patterns at the same time. The most useful parameters for the differential diagnosis were cell density, mitosis, zonation, infiltration pattern, and consumption of the epidermis. Assignation of a spitzoid melanoma to 1 of more of our 5 subtypes can enable a more confident diagnosis to be made.