Verocay body--prominent cutaneous schwannoma

Palisaded Encapsulated Neuroma: An Unusual Presentation

Palisaded encapsulated neuroma (PEN) is a distinctive benign neural tumor, which usually presents as a solitary skin-colored papule or a nodule. It is a benign lesion and may clinically mimic a cutaneous neurofibroma, melanocytic nevi, or cutaneous schwannoma. Here we report a rare case of multifocal cutaneous PENs and its differentiation from cutaneous schwannomas, which is possible by histopathology.

Zosteriform palisaded encapsulated neuroma: an unusual presentation

Palisaded encapsulated neuroma (PEN) is an infrequent benign cutaneous neural tumor, which usually presents as solitary, asymptomatic, papule or nodule, often localized on the faces, around the orifices, in middle age with no sex preponderance. Rarely, it can be multiple. Both solitary and multiple lesions are not associated with neurofibromatosis or multiple endocrine neoplasica syndrome type 2B (MEN 2B). We hereby report, a rare case of multiple cutaneous PEN in a 30-year-old female who presented with multiple asymptomatic soft-to-firm papules and nodules in a dermatomal distribution on the face along the supply of the ophthalmic division of the trigeminal nerve with no signs of neurofibromatosis or MEN 2B.

Cutaneous schwannoma masquerading as trichilemmal cyst over scalp in a young male

Schwannomas are benign tumors derived from Schwann cells. They are comparatively rare on scalp and easily mistaken for tumors of hair. Trichilemmal cysts are common over scalp and present as dermal or subcutaneous growths over scalp. We present a solitary schwannoma of scalp clinically mimicking trichilemmal cyst. The tumor was surgically excised and the same was confirmed by histopathology.

Cutaneous neoplasms with prominent Verocay body-like structures: the so-called "rippled pattern"

A striking appearance resulting from alternating areas of epithelial cell cords and stroma seen in some cutaneous adnexal neoplasms has been referred to as the "rippled pattern." Histologically, this pattern may be indistinguishable from Verocay bodies described in schwannomas. A number of common and clinically diverse cutaneous neoplasms can be linked by the presence of this unusual growth pattern. The heterogeneous group of tumors that have been known to demonstrate this feature includes those with epithelial, adnexal, fibrohistiocytic, mesenchymal, and melanocytic lineage. The objective of this review is to alert the dermatopathologist to the range of neoplasms, which can potentially show this attribute, so that a misdiagnosis can be avoided.

Low grade malignant peripheral nerve sheath tumor with smooth muscle differentiation

Malignant peripheral nerve sheath tumors are usually Schwann cell derived. Differentiation along mesenchymal lines is uncommon. Herein we present an example with smooth muscle differentiation occurring in the left distal forearm of a 62-year-old male with neurofibromatosis type I. Incisional biopsy of the slowly growing mass demonstrated a low-grade malignant peripheral nerve sheath tumor with strong S-100 protein immunoexpression as well as focal smooth muscle actin staining in atypical neoplastic cells. Immunostains for epithelial membrane antigen, neurofilament protein, glial fibrillary acidic protein, CD57, desmin, and myogenin were negative. The MIB-1 labeling index was 5.4%. Electron microscopy revealed arrays of microfilaments (actin myofilaments) variably associated with fusiform dense bodies, plasmalemmal micropinocytotic vesicles, and foci of external lamina (basement membrane) consistent with smooth muscle differentiation. Smooth muscle should be added to the spectrum of differentiation exhibited by malignant peripheral nerve sheath tumors. Its recognition requires exclusion of the alternative diagnosis of leiomyosarcoma.

Expression of ABCA2 protein in human vestibular schwannoma and peripheral nerve

ABCA2, which belongs to the A subclass of the ATP-binding cassette (ABC) transporter superfamily, is predominantly expressed in the cytoplasm of oligodendrocytes and Schwann cells, the myelin-forming cells in brain and peripheral nerve, respectively. Here, we demonstrate by immunoblot and immunohistochemistry that ABCA2 is expressed in benign vestibular schwannomas, which contain neither axons nor compact myelin. The expression patterns of ABCA2 in combination with other markers showed phenotypic heterogeneity in schwannomas. The majority of cells in fascicular Antoni type A areas coexpressed ABCA2, Ca2+-binding protein S100beta, and p75 nerve growth factor receptor. In contrast, considerably varied expression levels of ABCA2 and p75 were more prominent in hypocellular type B areas than in type A areas. These data suggest that ABCA2 may be useful as a marker for cellular characterization of schwannomas.

Palisaded and verocay body prominent leiomyoma of deep soft tissue

Leiomyoma of deep soft tissue is a very rare tumor, which is sometimes confused with leiomyosarcoma, histopathologically. We describe a case of palisaded and Verocay-body prominent leiomyoma of deep soft tissue. The lesion was characterized by areas of nuclear palisading with Verocay-body like formation in addition to the features of leiomyoma.

Structural variations of collagen in normal and pathological tissues: role of electron microscopy

The spectrum of ultrastructural appearances assumed by collagen in normal and pathological tissues is illustrated using techniques of thin section transmission electron microscopy and computer-assisted analysis. The normal fibrillar collagen types are described in order to provide a basis for comparing other normal and abnormal forms. In normal tissues, the anchoring fibril and basal lamina (basement membrane) represent tissue structures largely containing collagen but differing significantly in organisation from normal types I to III fibrillar collagen. In pathological tissue, deviations from normal fine structure are reflected in abnormal aggregates of collagen fibrils (amianthoid and skeinoid fibres) and abnormalities in fibril diameter and cross-sectional profile. Fibrous and segment long-spacing collagen represent two further organisational variants of collagen, the former found widely in pathological tissues, the latter very rarely. Much remains to be discovered about these abnormal collagen variants-their mode of formation, the cells that produce them, and their roles. They also present a challenge for the collagen biologist formulating hypotheses of collagen fibril assembly and molecular organisation.

Palisading and verocay body-prominent dermatofibrosarcoma protuberans: a report of three cases

The aim of this report is to draw attention to nuclear palisading and Verocay body formation as peculiar, previously undescribed histological findings in rare instances of dermatofibrosarcoma protuberans (DFSP).

METHODS AND RESULTS

Three indurated, nodular or plaque skin lesions were diagnosed as DFSP on the basis of their storiform proliferation of spindle-shaped cells diffusely infiltrating the dermis and subcutaneous tissue. Sclerosing and giant cell areas were also identified. Unexpectedly, conspicuous nuclear palisading was also noted in all cases and Verocay body formation was present in two. Immunostains were positive for CD34 and negative for S100 protein in every instance. Proliferating cells were seen to display fibroblast-like features by ultrastructural study of one case.

CONCLUSIONS

DFSP may rarely show a schwannoid histological appearance as the result of nuclear palisading and even Verocay body formation. In this setting, both the search for DFSP characteristic morphologic features and the performance of CD34 and S100 protein immunohistochemistry will facilitate the correct diagnosis.

Immunohistochemistry in diagnostic dermatopathology

This article briefly reviews many immunohistochemical stains that have been in use for years, emphasizing their diagnostic use and potential pitfalls. Several newer immunostains are described in a more comprehensive fashion, including brief summaries from recently published studies.