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Query: UMLS:C0027960 (mole)
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Melanocytic nevi may microscopically associate with clefts or slits of the nests resembling lymphatic or vascular spaces. This unique histologic feature has been known as an artifact of injection or tissue-processing. We present a case of melanocytic nevus with a prominent vascular space-like structure. We also studied whether intralesional injection of local anesthetic could reproduce similar histologic findings. A 45-year-old Japanese female visited us with a solitary, brownish papule on the chest. Histology revealed numerous nests composed of round to oval-shaped nevus cells throughout the entire dermis. In the mid-dermis, nevus cells were lined up in a layer anastomosing and forming a vascular space-like structure. These nevus cells were uniformly stained with vimentin and S100 protein but not with factor VIII-related antigen. They were also positively immunoreactive with anti-type IV collagen and anti-fibronectin. There were no significant differences in staining intensity in the nevus cells between the solid portion and the vascular space-like structure. In the experimental study, eight melanocytic nevi were removed under local anesthesia. The local anesthetic solution was then injected into the excised nevus. Intralesional injection of a considerable volume of local anesthetic was capable of causing slits or clefts of the nests and dermal edema; however, it failed to reproduce a vascular space-like structure similar to that in the present case. These findings suggest that a vascular space-like structure in melanocytic nevus is not caused by the injection alone. Some other factor(s) may play a major role in the development of such structures in melanocytic nevus.
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PMID:The vascular space-like structure in melanocytic nevus is not an injection artifact: report of a case and an experimental study. 957 74

We present five cases of a hitherto unreported cutaneous neoplasm. The tumors appeared as solitary slow-growing flesh-colored nodules arising in young and middle-aged adults. They were located on the trunk, the upper extremities, and the face, and did not recur after complete excision. Clinically, they were diagnosed as dermal nevus, Spitz's nevus, fibroma, or neurofibroma. Histology revealed polypoid flat-dome-shaped lesions with a sharply demarcated matrix consisting of coarse hyalinized collagen bundles arranged in a prominent storiform pattern and separated by mucin-containing clefts. Despite a low overall cellularity, the tumors contained numerous, occasionally bizarre-shaped, multinucleate giant cells with crowded vesicular nuclei and a pale staining foamy cytoplasm, as well as plump fibroblastlike cells with analogous nuclear morphology. Atypical nuclei or mitotic figures were not observed. The cells were strongly positive for vimentin but negative for cytokeratin, smooth muscle actin, desmin, S-100 protein, CD34, factor XIIIa, and the macrophage markers KP1, Mac 387, and Ki-M1p, suggesting a fibroblastic origin. Based on the overall architecture, we conclude that these tumors probably represent a distinctive variant of solitary circumscribed storiform collagenoma (sclerotic fibroma) and propose the designation of giant cell collagenoma.
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PMID:Giant cell collagenoma: a benign dermal tumor with distinctive multinucleate cells. 959 25

The presence of eosinophilic globules has been described as a helpful sign for the histologic differentiation of Spitz's nevus from malignant melanoma. The origin of these bodies is not clear, and they have been likened to Civatte or colloid bodies of lichen planus. This would suggest that they might originate from degenerating keratinocytes or melanocytes or both. These eosinophilic globules and the colloid bodies of lichen planus have been reported to be similar in that they both stain positively for type IV collagen and laminin. These previous reports have failed to include, or have not emphasized, the staining for keratin that separates these two bodies. We stained 10 spindle cell and epithelial cell (S&E) nevi for S-100 protein, keratin, vimentin, type IV collagen, and laminin. In all 10 cases of S&E nevi, the eosinophilic globules showed a positive reaction for type IV collagen and laminin and a negative reaction for keratin, S100 protein, and vimentin, unlike the colloid bodies of lichen planus, which showed a negative reaction for type IV collagen and laminin and also a strong positive reaction for keratin. These results suggest that the eosinophilic globules of Spitz's nevi are basement membrane material, perhaps synthesized by either basal cells, melanocytes or both, and are not degenerated basal cells or melanocytes.
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PMID:Eosinophilic globules in spindle cell and epithelioid cell nevi: composition and possible origin. 985 49

Adequate interpretation of clinical and histopathologic features of giant congenital melanocytic nevus (GCMN) in newborns is a continued challenge. A GCMN with three large nodules and three polypoid exophytic tumors presented in the dorsum of a female full-term newborn, the borders exhibiting a spotted grouped pattern. Microscopic examination revealed a peculiar adnexal-centered (eccrine sweat gland ducts, acrosiringia, and hair infundibula) compound nevus expressing pagetoid intraepidermal spreading of epithelioid melanocytes. The nodules represented an extensive ganglioneuromatous component. The neurons and their neuropil were positive for neuron-specific enolase, S-100, synaptophysin, tyrosine hydroxilase, and PGP 9.5. In addition to these components, a poorly differentiated, fusiform, low-mitotic rate population of cells undergoing epithelioid differentiation (and probably neuronal differentiation) with nodular arrangement was also present in the polypoid tumors and deeper parts of the nevus, in part intermixed with the neurons. These cells were vimentin positive but S-100 negative. FISH studies revealed these cells to express three signals for the centromeric probe for chromosome 7 whereas the neuronal component showed just two. Adnexal-centered arrangement of melanocytes has not been emphasized in GCMN. Ganglioneuromatous differentiation has been rarely reported in this condition. Trisomy 7 in GCMN has been reported only once previously.
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PMID:Adnexal-centered giant congenital melanocyte nevus with extensive ganglioneuromatous component and trisomy 7. 1044 25

Primary malignant melanoma of the mediastinum is extremely rare. We report a case not previously reported of primary malignant melanoma located in the mediastinum in a 11-year-old boy. The tumor could not be completely resected as a result of extensive invasion of the large blood vessels. Histologically, the tumor was heavily pigmented and composed of vague fascicles of spindle cells intermingled with epithelioid cells. Immunohistochemical analysis showed vimentin, S-100 protein, Melan-A, and HMB-45 immunoreactivity in most of the tumor cells. Nearly 50% of the tumor cells were also positive for p53. It is suggested that primary malignant melanoma of the anterior mediastinum may have a histogenetic relationship to the recently described aggregates of nevus cells in the thymus or mediastinal lymph nodes.
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PMID:Primary malignant melanoma of the anterior mediastinum in a child. 1080 Sep 95

A case of gallbladder involvement by malignant melanoma in a 57-year-old woman is reported. The gallbladder, resected for cholelithiasis, harboured a pedunculated polypoid dark mass, which histologically revealed sheets and nests of epithelioid cells with hyperchromatic nuclei in the lamina propria and at the junctional level. These cells were pigmented (with positive reaction with Schmorl's stain and bleaching with peroxide) and showed immunohistochemical positivity for S-100, gp 100 antigen (HMB-45 antibody) and vimentin. The patient, affected by dysplastic naevus syndrome, had a melanoma in situ excised from the scalp 8 years earlier. The features of the investigated lesion address towards a diagnosis of primary gallbladder melanoma. Furthermore, this is the first time that the existence of such a controversial entity is sustained by the ultrastructural investigation of melanosomes, demonstrating the presence of two melanocitary populations, a typical one exclusively junctional and an atypical one both at the junctional level and in the lamina propria.
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PMID:Primary malignant melanoma of the gallbladder in dysplastic naevus syndrome. 1125 18

Connective tissue consists of collagen, elastic fibers and ground substances produced by fibrocytes. These cells are usually spindle-shaped with slender nuclei and bipolar cytoplasmic extensions. Apart from labeling for vimentin and variable reactivity for factor XIIIa and CD34, fibrocytes are immunonegative. Electron microscopy reveals prominent endoplasmic reticulum, but is otherwise indistinct. Lesions with fibrocytic differentiation can be divided into five categories: scars, keloids, dermatofibromas, nodular fasciitis, and superficial fibromatoses are inflammatory lesions. Thereby, dermatofibromas and their subcutaneous/deep soft tissue counterpart nodular fasciitis can present with a wide variety of clinicopathologic variants which may be misinterpreted as malignancies. Prurigo nodularis, chondrodermatitis nodularis helicis, acanthoma fissuratum, and knuckle pads are hyperplasias; fibroma molle, fibrous papules, connective tissue nevi, and elastofibroma are hamartomas; and fibroma of tendon sheath, pleomorphic fibroma, and giant cell tumor of tendon sheath are benign neoplasms. Deep fibromatoses, dermatofibrosarcoma protuberans, giant cell fibroblastoma, giant cell angiofibroma, hyalinizing spindle cell tumor with giant rosettes, solitary fibrous tumor, myxofibrosarcoma, low-grade fibromyxoid sarcoma, acral myxoinflammatory fibroblastic sarcoma, and classical fibrosarcoma, are malignant neoplasms, that is fibrosarcomas of variable malignant potential. Lesions dominated by myocytes/ myofibroblasts, e.g. cutaneous myofibroma/infantile myofibromatosis, or by macrophages, e.g. xanthogranulomas, are not part of this chapter.
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PMID:Connective tissue tumors. 1207 32

Rosette formation is a feature that has not been described as occurring in melanocytic neoplasms. We present such a unique case. A 59-year-old man presented with an asymptomatic, soft, hairy 3.0 x 2.0-cm pigmented lesion that had been present for many years in the right external ear, extending from the conchal bowl onto the antitragus area. Examination of histologic sections showed a proliferation of nonatypical and heavily pigmented melanocytes in the superficial dermis and around deep adnexal structures, characteristic of a congenital nevus. In other areas, pigmented spindled and dendritic cells infiltrated thickened collagen bundles in a pattern of a blue nevus. A nodular proliferation of epithelioid melanocytes was seen within the deep dermis and subcutaneous tissue. The periphery of the nodule merged with the surrounding nevus cells. Neoplastic cells with nuclear atypia, melanin pigment, pseudonuclear inclusions, and balloon cell change were present. In addition, there was rosette formation by the tumor cells, with a central aggregate of coarse cell processes. Neuroid cords were also noted. No prominent mitotic figures, necrosis, or significant inflammatory infiltrate were noted. The neoplastic cells were positive for S-100 protein, Mart-1, tyrosinase, neuron-specific enolase, and vimentin. HMB-45 and Ki-67 (MIB-1) labeled only rare neoplastic cells within the proliferative nodule. The tumor cells were negative for synaptophysin, protein gene product 9.5, CD57, epithelial membrane antigen, CD31, and CD34. The central cell processes of the rosettes were negative for trichome, type IV collagen, neurofilament protein, glial fibrillary acidic protein, and tyrosine hydroxylase. We also retrospectively examined 78 congenital nevi of 65 pediatric patients at our institution. Rosette formation was not seen in any of these cases.
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PMID:Rosette formation within a proliferative nodule of an atypical combined melanocytic nevus in an adult. 1287 2

Eleven cases of seborrheic keratoses with desmoplastic stroma and associated nests and cords of squamous epithelium simulating infiltrating carcinoma are presented. There were 7 males and 4 females ranging in age from 44 to 88 years (mean = 62). Eight cases were on the head and neck, one each on the lower and upper extremity, and one on the pubic area. Clinical diagnoses included seborrheic keratosis, squamous and basal cell carcinoma, and dermal nevus. Histologically, the lesions were characterized by exophytic growth pattern of basaloid and squamous cells, without cytologic atypia, and well-demarcated peripheral borders, typical for that seen in seborrheic keratoses. Squamous eddy formation with parakeratosis and spongiosis was present in all cases. Located within the body of the lesions were irregular nests and cords of squamous cells extending into the surrounding dermis with associated fibroblastic dermal proliferation trapping the epithelial nests, simulating invasive carcinoma. Immunohistochemically, the epithelial nests were cytokeratin positive and HPV negative, and the dermal stromal cells were vimentin positive and factor XIIIa, cytokeratin, and CD34 negative. Adjacent changes of carcinoma, trichilemmoma, verruca, or other adnexal neoplasm were not identified. Seborrheic keratoses may demonstrate desmoplastic changes analogous to that seen in desmoplastic trichilemmomas. Awareness of these changes in seborrheic keratosis will avoid misdiagnosis and excessive therapy.
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PMID:Desmoplastic seborrheic keratosis. 1277 83

A 54-year-old man presented with a recurrent swelling on the right occipital region of the scalp. Two months earlier, the patient had undergone an initial local excision of the lesion which had enlarged progressively over the previous 2 years on a hairless patch which had been present since birth. On examination, a 5 x 4-cm, pinkish, firm, ulcerated swelling was seen on the right occipital region with a scar running over it. The lesion was not fixed to the underlying bone and there was no regional lymphadenopathy. X-Ray of the skull was normal and no evidence of metastatic disease was identified. Wide local excision of the tumor was performed and it was sent for histopathologic examination. Specimens and slides of the earlier surgery performed elsewhere were also studied. The specimen of the initial surgery consisted of skin-covered tissue with an exophytic firm growth measuring 6 x 5 x 4 cm. The skin surface was rough with areas of ulceration. No necrosis was noted grossly. Microscopically, three distinct lesions were seen. One was a well-circumscribed tumor located in the superficial dermis with lobules of basaloid cell aggregates with peripheral palisading and with no epidermal connection. The lobules were surrounded by cellular fibrous tissue (Fig. 1). Unlike basal cell carcinoma, however, no cleft between the cellular aggregates and stroma was noted. Foci of pigmentation were seen within cellular lobules and these features were consistent with a diagnosis of tricho-blastoma. The second tumor was seen adjacent to the first, and consisted of duct-like structures and cystic spaces with papillary projections. These were lined by double-layered epithelium with stromal infiltration by plasma cells, which are features of syringocystadenoma papilliferum (Fig. 2). The third lesion was a spindle cell sarcoma which formed the major part of the lesion, diffusely infiltrating the dermis and subcutaneous tissue, elevating and ulcerating the overlying skin. The tumor consisted of interlacing fascicles of spindle cells with oval to elongated nuclei having finely dispersed chromatin and inconspicuous nucleoli. The tumor cells were seen encircling the sweat glands, without destroying them (Fig. 3). Nuclear pleomorphism was minimal, with a mitotic rate of 9-10 per high-power field. A small area of epidermal hyperplasia with acanthosis and papillomatosis overlying malformed highly placed sebaceous glands was the only evidence of a pre-existing nevus sebaceus. The status of the surgical margins was not clearly discernible. The wide excision specimen of the recurrent swelling consisted of a skin-covered nodule with ulceration, measuring 3 x 4 x 3 cm, with a gray-white whorled cut surface. No necrosis was noted grossly. Multiple sections showed only spindle cell sarcoma infiltrating the skin and subcutaneous tissue, morphologically similar to the earlier tumor, with ulceration of the overlying skin. The surgical margins were free from tumor. Immunohistochemical stains on the spindle cell sarcoma showed positive staining for smooth muscle actin (SMA) (Fig. 4), vimentin, epithelial membrane antigen (EMA), and S100. The tumor cells were negative for cytokeratin (CK), HMB45, desmin, glial fibrillary acidic protein (GFAP), CD34, and CD68. Correlating the histomorphology and immunohistochemical findings, a diagnosis of cutaneous leiomyosarcoma with tricho-blastoma and syringocystadenoma papilliferum arising on nevus sebaceus was made. The patient received postoperative radiotherapy and is disease free 8 months after diagnosis.
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PMID:Cutaneous leiomyosarcoma, trichoblastoma, and syringocystadenoma papilliferum arising from nevus sebaceus. 1734 92


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