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Notes: We report two patients with the typical clinical (patches/plaques studded with brownish-red papules) and histopathological (hyperplastic eccrine ducts and glands surrounded and infiltrated by lymphocytes) features of syringotropic cutaneous T-cell lymphoma. Immunohistochemical studies confirmed the T-cell character of the infiltrate, and gene rearrangement studies its monoclonality (in one case). Our patients did not present with visceral involvement.

Notes: Aims: Based on a series of 25 cases, we define and characterize combined dermatofibroma, a tumour comprising two or more variant patterns of dermatofibroma in a single lesion.〈section xml:id="abs1-1"〉〈title type="main"〉Method and resultsDermatofibroma may present with a wide variety of architectural, cellular or stromal peculiarities. Architectural peculiarities include deep penetration, atrophy, collarette formation, fascicular to plexiform architecture, massive haemorrhage, prominent haemangiopericytoma-like vascularity and palisading; cellular peculiarities the presence of epithelioid cells, clear cells, granular cells, prominent myofibroblastic differentiation and atypical giant cells (‘monster cells’); or stromal peculiarities such as prominent sclerosis, mucin, haemosiderin and cholesterotic deposits. In combined dermatofibromas two or more of these features are seen in complex or inhomogenous combination such as the silhouette of a deep penetrating dermatofibroma with an ‘ordinary’ storiform pattern in the upper and granular cell differentiation in the lower part of the lesion; or a dermatofibroma with ordinary features in the upper, prominent sclerosis in the middle and clear cells in the lower portion of the lesion; or the characteristic epidermal collarette and cells of epithelial cell histiocytoma with a plexiform (‘neurothekeoma-like’) architecture surrounded by a myxoid stroma with spindle-shaped to stellate cells. Clinically, these lesions preferentially occur on the lower extremities of young to middle-aged females, frequently with the diagnosis of a fibrohistiocytic lesion. Apart from one recurrence follow-up was uneventful in all other cases. Immunohistochemically, lesions are consistently positive with KiM1p, variably positive for factor XIIIa, smooth muscle specific actin and with KP1 (CD68), NK1C3 and E9.〈section xml:id="abs1-2"〉〈title type="main"〉ConclusionRecognition of combined dermatofibroma allows the histopathologist to apply a confident benign label to unusual lesions which might otherwise elude diagnosis, or tempt description of ‘new’ entities and to avoid a misdiagnosis of malignancy.

Notes: Summary Sequential biopsies taken from a patient with a solitary giant xanthogranuloma, an exaggerated macronodular (〉5 cm in diameter) variant of juvenile xanthogranuloma, and from a patient with benign cephalic histiocytosis, revealed a characteristic time sequence of histopathological findings. Early stages of the diseases showed a monomorphous infiltrate of mononuclear vacuolated histiocytes positive for KiM1p. HAM56 and factor XIIIa and were characterized by clusters of comma-shaped bodies. This was followed by a polymorphous mixture of various mononuclear and mullinucleate histiocytes additionally labelling with KP1 (CD68) and, in occasional cells, for the adherence of peanut agglutinin. A variety of ultrastructural changes were found, including dense and regularly laminated bodies or lipid droplets. Our findings indicate that both entities are variants of a xanthogranulomatous reaction.

Notes: Summary We recently examined a patient who presented clinically with tender, erythematous papules associated with a febrile illness and polyarthralgias. Histopathological examination revealed extravascular palisaded neutrophilic granulomas, a skin reaction pattern originally described in Churg–Strauss disease but subsequently observed in a variety of other systemic disorders characterized by immune complex generation. A diagnosis of systemic lupus erythematosus (SLE) was established. To our knowledge, this is the first report of extravascular necrotizing palisaded granulomas as the presenting skin sign of SLE.

Notes: Four endothelial cell markers, two selective cytokeratin markers and a monoclonal smooth muscle antibody (SMA) were employed in the assessment of 19 cases of cutaneous angiosarcoma classified according to their degree of tumour differentiation. No labelling was seen for SMA or with cytokeratin markers MNF116 and CBL170. Expression of factor VIII-related antigen was seen in two tumours and positivity for CD34 (QBend 10 antibody) was found in four tumours. By contrast the pan-endothelial cell marker Ulex europeaus agglutinin 1 (UEA-1) and the CD31 marker JC70A labelled all cases of cutaneous angiosarcoma with the exception of one poorly differentiated tumour. These data confirm the endothelial cell origin of angiosarcoma, they demonstrate that CD31 and UEA1 are reliable markers in routinely processed tissue, and they suggest a lymphatic derivation for the tumour. This finding is in marked contrast to Kaposi‘s sarcoma where CD34 is the most reliable marker.

Notes: Metallothioneins are ubiquitous proteins with a high affinity for heavy metal ions, e.g. zinc, copper and cadmium. Experimentally, metallothionein over-expression in cell lines derived from a variety of cancers has been associated with resistance to anticancer drugs and irradiation therapy. Using a monoclonal antibody (E9) to metallothionein we investigated immunoreactive expression in routinely fixed and paraffin-embedded tissue from 63 cases of malignant melanoma and 13 secondary deposits. Whereas a variety of cells in normal skin showed metallothionein expression, all forms of benign naevi studied were uniformly negative. In contrast 13/30 ‘thin’ (≤1.5 mm; 0.7 ± 0.4). 25 29 ‘thick’ malignant melanoma (〉 1.5 mm; 5.5 ± 3.9) and 12/13 metastases were positive. Six patients with thin and 19 with thick melanoma with metallothionein expression died during a mean observation period of 6.4 ± 1.8 and 3.6 ± 2.5 years, respectively, their survival distribution function analyses giving statistically significant results for both the vertical tumour thickness (P 〈 0.0001) and metallothionein expression (P 〈 0.0001). These immunohistochemical results, based on routinely processed paraffin-embedded tissue, suggest that metallothionein expression in malignant melanoma is significantly associated with progressive disease and might therefore be a useful prognostic indicator.

Notes: 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.

Notes: To describe a series of five granular cell dermatofibromas as an unusual and rare manifestation of fibrohistiocytic tissue response.〈section xml:id="abs1-2"〉〈title type="main"〉Methods and results:Five granular cell dermatofibromas were collected out of 136 tumours filed as granular cell tumours. Clinically, all lesions occurred on the shoulder or back of middle-aged adults (two women, three men), mostly with the clinical diagnosis of a fibrohistiocytic lesion. Histology revealed well-circumscribed, dermal to subcutaneous lesions dominated by periodic acid–Schiff (PAS) positive, granular cells. Acanthosis above, as well as storiform arrangement of spindle cells, sclerotic collagen and some interspersed lymphohistiocytic infiltrate at the periphery of the lesion, indicated the fibrohistiocytic origin. Lesions showed prominent reactivity with NK1C3 (CD57), as well as for macrophage markers KiM1p and KP1 (CD68). In contrast to classic Schwannian/neurogenic granular cell tumours, granular cell dermatofibromas were S100 protein negative, but showed variable reactivity for factor XIIIa (10–50%) in 4/5, for smooth muscle specific actin (10–50%) in 2/5 and with E9 (10–30%) in 3/5 lesions. Electron microscopy in one case revealed large pools of phago-lysosomes and variably sized glycogen granules in granular cells.〈section xml:id="abs1-3"〉〈title type="main"〉Conclusion:Our series delineates granular cell dermatofibroma as a distinct clinicopathological variant of fibrohistiocytic tissue response which needs to be distinguished from other tumours with granular cell features.