Hansjörg Steiner

Cellular 'neurothekeoma' : an epithelioid variant of dermatofibroma?

Cellular neurothekeoma is a rare benign cutaneous neoplasm with conflicting opinions regarding its histogenetic origin (nerve sheath, smooth muscle, myofibroblasts) as well as its relation to myxoid neurothekeoma (nerve sheath myxoma). The present series describes 15 cases whose clinicopathological features indicate a relationship to dermatofibroma.

Clear cell dermatofibroma : Case report of an unusual fibrohistiocytic lesion

A case of clear cell dermatofibroma is presented. Clinically, a 41-year-old woman exhibited a hard brown nodule on her instep that was assumed to be a dermatofibroma. Histologically, more than 90% of the lesion was composed of clear cells. Epidermal hyperplasia and a storiform arrangement of spindle cells and sclerotic collagen in some foci at the periphery of the lesion indicated the fibrohistiocytic origin. Moreover, prominent vascularity and some bizarre giant cells in the lower part of the lesion were reminiscent of multinucleate cell angiohistiocytoma. Of a broad panel of antibodies, the lesion was positive only for Factor XIIIa (and vimentin). Ultrastructurally, clear-cell changes corresponded to a mostly translucent cytoplasm, focally with some endoplasmic reticulum and prominent lysosomal structures. A review of 1,496 dermatofibromas seen during the last 15 years at our institute revealed 12 cases (1%) with similar clear-cell changes in a minor part of the infiltrate (less than 10%). The differential diagnosis includes metastases of renal-cell carcinoma, which exhibit more atypia and mitoses and are positive for epithelial cell markers; clear-cell sarcoma, a lesion of tendons or aponeurosis with some moderate cytoplasmic melanin deposition and immunoreactivity with HMB-45; and various non-X histiocytic disorders, such as the predominantly vacuolated type of juvenile (or adult) xanthogranulomas or papular xanthoma, with a mixed infiltrate of various types of mononuclear and multinucleate histiocytes positive with a variety of macrophage markers.

Clear cell dermatofibroma

This series presents six cases of a rare variant of dermatofibroma, characterized by marked clear cell change. All lesions occurred on the lower extremities of middle‐aged adults (four women, two men), mostly with the clinical diagnosis of fibrohistiocytic lesion. Histological examination revealed well circumscribed, faintly stained dermal to subcutaneous lesions which were due to the overwhelming presence of clear cells (<90%), some with prominent PAS‐positive cytoplasmic granulation. Overlying epidermal hyperplasia as well as storiform arrangement of spindle cells, sclerotic collagen and some interspersed lympho‐histiocytic infiltrate at the periphery of the lesion indicated the fibrohistiocytic origin. Individual histopathological peculiarities included : bizarre giant cells in two cases, prominent perivascular lympho‐histiocytic response, perifollicular arrangement and haemangiopericytoma‐like features with iron deposition in one case each. Immunohistochemically three of four lesions showed moderate reactivity for factor XIIIa and two of four with an anti‐metallothionen marker E9, but were otherwise negative with a broad panel of markers. Electronmicroscopy in two cases revealed large pools of glycogen beside focal, prominent endoplasmic reticulum and lysosomes in some granular cells, but only optically translucent cells in cases of clear cells. Recognition of clear cell dermatofibroma is important as the differential diagnosis includes some entities with more serious outcome/considerations such as metastases of renal cell carcinoma, xanthogranulomatous reactions, balloon cell naevus/melanoma and clear cell sarcoma.

Granular cell dermatofibroma

To describe a series of five granular cell dermatofibromas as an unusual and rare manifestation of fibrohistiocytic tissue response.

Malignant melanomas simulating various types of soft tissue tumors.

background Primary malignant melanomas, recurrences, and metastases thereof can present with a wide variety of clinicopathologic aspects. objective The present series describes eight primary malignant melanomas and/or 10 local recurrences/metastases (from eight patients) misdiagnosed as various types of soft tissue tumors: two dermatofibrosarcoma protuberans, two atypical fibroxanthomas, rim storifoirmplcomorphic malignant fibrous histiocytomas, one myxofibrosarcoma (“myxoid malignant fibrous histiocytoma”), two malignant hemangiopericytomas, and nine malignant schwannomas. methods In three cases correct diagnosis was established by clinicopathologic correlation during follow‐up; all the others were only discovered during a retrospective work‐up of all soft tissue tumors diagnosed at the Dermatohistopathological Laboratory of the Department of Dermatology, University of Innsbruck. results Helpful clues derived from subtle intraepidermal, irregular spread of melanocytes, focal nested arrangement of tumor cells, sparse melanin deposition, neurotropism, and prominent peripheral lymphohistiocytic response, partially forming lymph follicles. Besides clinicopathologic correlation, histology of serial sections as well as iminunohistodiemistry (S100 protein more important than NK1/C3; HMB45 without benefit) and electron microscopy (melatiosomes) proved helpful for definitive diagnosis. In contrast to the general assumption that spindle cell/desmoplastic malignant melanomas have an unequivocal bad prognosis, our series, as well as evidence from the literature, document a better prognosis than that of other types with comparable tumor thickness (70% us 50% 5‐year survival). Moreover, labeling with E9, an antimetallothionein marker, confirmed its usefulness for prognosis being strongly positive in primary lesions followed by rapid progression, but mostly negative in those without. conclusion These cases document that malignant melanoma may mimic various types of soft tissue tumors; correct interpretation is important as prognosis and therapeutic management differ considerably between these entities.

Dermal spindle cell lipoma: plexiform and nodular variants

We report on eleven cases of a distinctive dermal spindle cell lipoma characterized by a mixture of mature adipocytes and spindle‐shaped cells in a fibromucinous background. Six lesions showed a moderately well circumscribed plexiform pattern, five a well demarcated nodular pattern with compression of surrounding connective tissue and prominent stromal fibrosis. Clinically, the plexiform type mostly occurred in the thigh‐groin‐buttock area and the nodular type in the head‐neck or acral location. While plexiform lesions were predominantly seen in middle‐aged females, nodular types occurred in young adults of either sex. No recurrence was seen in five patients with follow‐up. The tumour cells were vimentin positive and a thin cytomplasmic rim of S‐100 protein positivity was seen in mature adipocytes. Ultrastructural studies revealed lipoblastic differentiation of spindle‐shaped cells with lipid droplets and basal lamina formation. Dermal spindle cell lipomas seem to be the dermal counterpart of the most subcutaneously located spindle cell lipoma.

Sclerotic lipoma : lipomas simulating sclerotic fibroma

Aims: We report a series of five unusual subcutaneous lipomas characterized by prominent stromal sclerosis in a storiform arrangement. Methods and results: All lesions occurred in young male adults (23.0  ±  9.5 years), three lesions were on the scalp and two on the hands. Clinically, lipoma, chondroma or some form of cyst were suspected. In contrast to sclerotic fibroma (‘circumscribed storiform collagenoma’) a variable number of adipocytes were interspersed within the fibrosclerotic background. These cells also showed immunoreactivity for S100 protein as well as intracytoplasmic lipid deposits ultrastructurally. None of the lesions recurred within a follow‐up period of between 0.5 and 9 years. Conclusions: Our series suggests that sclerotic lipomas should be classified with fibro‐ and myxolipomas, angiolipomas, spindle cell and pleomorphic lipomas, as an additional characteristic subtype of lipoma. Sclerotic lipomas are often misdiagnosed as a sclerotic fibroma, but are essentially fatty tumours and are, at least in our small series, not associated with Cowdens disease.

Retiform hemangioendothelioma: presentation of a case expressing D2-40.

Retiform hemangioendothelioma (RH) is a low‐grade angiosarcoma with low metastatic risk, usually occurring as a single lesion on the trunk or extremity in middle‐aged adults. Histopathology shows a distinctive pattern with arborizing blood vessels arranged in a retiform pattern (similar to rete testis tissue) and focal papillae with fibrosclerotic (hyaline) cores. The blood vessels are lined by comparatively monomorphic endothelial cells, frequently presenting a hobnail pattern. We report a case of RH presenting as an indolent brownish plaque on the back of a 17‐year‐old male. Surgical resection and sentinel lymph node biopsy showed no evidence of metastasis. In contrast to the recent literature, this case of RH showed positivity for D2‐40, a marker of lymphatic endothelium. We also report ultrastructural findings for this case of RH.

Cutaneous epithelioid hemangioendothelioma, epithelioid cell histiocytoma and Spitz nevus. Three separate epithelioid tumors in one patient

We report the unusual history of a young lady who, over a period of 9 years, developed 3 epithelioid neoplasms of different histiogenetic origin: a cutaneous epithelioid hemangioendothelioma, an epithelioid cell histiocytoma, and a Spitz nevus. To the best of our knowledge, such an unusual combination of neoplasms has not been reported previously and raises the question of an underlying “epithelioid” reaction pattern responsible for the epithelioid appearance in all 3 tumors; the likelihood of such a combination of tumors occurring in a single patient would be less than 1 in 1 billion.