Regressing atypical histiocytosis and lymphomatoid papulosis: variants of the same disorder?

We report a patient with lymphomatoid papulosis who developed a lesion with the clinicopathological features of regressing atypical histiocytosis. Immunohistochemical studies supported a T-cell histogenesis and many of the atypical cells demonstrated BerH2 (Ki-I antigen) positivity. The case supports the view that regressing atypical histiocytosis and lymphomatoid papulosis are different manifestations of the same disease spectrum.

The heterogeneity of Jessner's lymphocytic infiltration of the skin. Immunohistochemical studies suggesting one form of perivascular lymphocytoma

Seventeen patients (six women and 11 men) with Jessner's lymphocytic infiltration of the skin were studied. Nineteen biopsy specimens were analyzed with the following monoclonal antibodies: UCHL1 (T cells), 4KB5, L26 (B cells), LN1 (germinal center B cells), and BerH2 (Ki-1+ cells). Routine direct immunofluorescence was performed on 15 specimens. In 10 of 19 specimens both B and T cells were demonstrated; the B cells were in close proximity to small blood vessels. In 50% of these cases the B cell component expressed LN1 positivity. We use the term perivascular lymphocytoma to describe this pattern. Nine specimens showed T cells only. No Ki-1+ cells were detected. Routine immunofluorescence studies were performed on 15 specimens. In six of seven specimens in which there was a mixed cell population of B and T cells, results were completely negative. In contrast, six of the remaining eight specimens with a predominantly T cell population revealed weak, patchy, granular, positive labeling for immunocomponents, particularly IgM and C3 at the basement membrane. These findings suggest that Jessner's lymphocytic infiltration is a heterogeneous disorder with at least two separate immunophenotypes. The finding of perivascular follicular center differentiation in more than half the specimens suggests a possible relationship in these cases to other benign lymphoid hyperplasias (pseudolymphomas).

A study of factor XIIIa and MAC 387 immunolabeling in normal and pathological skin

Immunolabeling with two new antibodies, Factor XIIIa and MAC 387, has been studied in routinely processed biopsy specimens of normal skin, subcutaneous tissues, lymph nodes, and a variety of pathological conditions. These presumptive cell markers of the monocyte-macrophage lineage appear to label totally different and possibly mutually exclusive subsets of cells. In normal skin, Factor XIIIa labeled fixed dermal connective tissue cells, emphasizing their dendritic morphological appearance. Factor XIIIa expression in fibroproliferative conditions and spindle cell tumors varied: in particular, scars, keloids, and dermatofibrosarcomas do not label, whereas histiocytomas, fibrous papule of the nose, and atypical fibroxanthomas were well labeled. In inflammatory conditions, increased numbers of Factor XIIIa cells were found, but most macrophages and epithelioid and multinucleate cells did not label. In contrast, normal dermal connective tissue cells did not label with MAC 387, nor did the constituent cells of various fibroproliferative disorders. In inflammatory conditions, variable numbers of MAC 387-positive cells were observed, corresponding to histiocytes and macrophages, but labeling of epithelioid cells and multinucleate foreign body giant cells was variable. Histiocytosis X cells do not express either label. The theoretical and practical implications of these results are explored.

Multinucleate cell angiohistiocytoma: an acquired vascular anomaly to be distinguished from Kaposi's sarcoma

Multinucleate cell angiohistocytoma is a newly described benign vascular condition that usually arises on the extremities of women over the age of 40 as discrete grouped violaceous erythematous papules, often mimicking Kaposi's sarcoma. Of 10 patients, nine were women aged between 37-66 (average 51.5) years at the onset of their condition. The legs, and in particular the calves and thighs, were the commonest sites to be involved. However, in three patients the papules were confined to the back of the hands, and the male patient had lesions across the front of the chest. Bilateral lesions occurred in four patients. Histologically, the salient features were proliferation of capillaries and small venules at the level of the subpapillary plexus and the mid dermis, in association with prominent connective tissue cells and larger angulated multinucleate cells. Detailed histochemical and immunocytochemical studies have not elucidated the histogenesis of the multinucleate cells that seem to be a characteristic feature of this condition.

Cutaneous extramedullary hematopoiesis with a preponderance of atypical megakaryocytes in myelofibrosis

Extramedullary hematopoiesis was found in the cutaneous papulonodular eruption of a 72-year-old man with myelofibrosis. This is the first reported case to show a preponderance of atypical megakaryocytes in skin lesions. The patient was also unusual in that he had marked generalized lymphadenopathy. The skin lesions almost disappeared after treatment with hydroxyurea.

Postfixation of cryostat sections improves tumor definition in Mohs surgery

Precise identification and localization of tumor is the key to success in Mohs micrographic surgery. In a pilot study, we demonstrated improvement in tumor definition and staining characteristics after formalin fixation of cryostat sections (postfixation) when compared with unfixed specimens. We further investigated the benefits of postfixation with a series of tissue fixatives and with varying fixation times. In all cases, postfixation was found to be beneficial. No improvement was noted by extending the postfixation time beyond 1 minute.

Characterization of factor XIIIa positive dermal dendritic cells in normal and inflamed skin

The immunocytochemical identification and characterization of indigenous dermal dendritic cells (dermal dendrocytes) using a rabbit polyclonal antibody to clotting enzyme factor XIII subunit A (FXIIIa) was carried out on normal and inflamed human cutaneous tissue. The immunophenotype of FXIIIa positive dendritic cells was analysed with a panel of 18 monoclonal antibodies using immunoperoxidase and double immunofluorescence staining techniques. The antibody against FXIIIa detected highly dendritic dermal cells located particularly in the upper reticular and papillary dermis. Double fluorescence microscopy showed that FXIIIa positive cells were bone marrow derived (HLe-I+) and co-expressed monocyte, macrophage or antigen presenting cell markers (HLA-DR+, LFA-I+, HLA-DQ+, OKM5+, Mo I+, Mono-I+, Leu M3+). No labelling was obtained with cell markers for Langerhans cells (CDI), T lymphocytes (CD2), granulocytes (LeuMI) fibroblasts (Te7), intercellular adhesion molecule-I (ICAM-I) or endothelial cells (Factor VIII related antigen). Gamma interferon induced increased expression of HLA-DR and co-expression of ICAM-I on FXIIIa+ dermal dendritic cells in normal skin in organ culture. Moreover, in benign inflammatory dermatoses such as atopic eczema and psoriasis there was an increased number of FXIIIa+, DR+, ICAM-I+ cells in the upper dermis and foci of FXIIIa+ cells in the epidermis closely associated with lymphocytes. FXIIIa positive cells in human skin represent a specific population of bone-marrow dermal dendritic cells, distinct from Langerhans cells, that share some features common to mononuclear phagocytes (monocyte/macrophages). In addition, the detection of HLA-DQ on 48% of FXIIIa+ cells and the lack of OKMI in combination with high OKM5 expression suggests an antigen-presenting cell phenotype.

An immunohistochemical study of fibrous papule of the nose: 25 cases

Twenty-five cases of fibrous papule of the nose were studied by light microscopy and by immunohistochemistry using a panel of 4 cell markers. These included polyclonal antibodies against S100 protein and Factor XIII-a (FXIII-a), and 2 monoclonal antibodies, MAC 387 which labels monocyte derived macrophage cells and Ulex Europaeus Agglutinin-1 (UEA-1) a pan endothelial cell marker. An increase in the number of S100 protein positive cells, particularly in the upper dermis, was observed in 3 lesions. Melanin was identified in phagocytes in the superficial dermis in 6 lesions, including those with S100 protein positive cells. In all of the papules there was a marked increase in FXIII-a labelling of dendritic connective tissue cells, including spindle, stellate and multinucleate stellate cells. Immunoreactivity with FXIII-a was especially strong in the increased mononuclear dendritic cell population (greater than 80%) seen in the mid- and upper dermis. However, only 15% of the larger multinucleate stellate cells were immunostained with FXIII-a. The results achieved with markers to the macrophage cell series (MAC 387) or endothelial cells (UEA-1) showed no significant increase in labelling of the dermal cell population compared to normal skin taken from the nose. Our study suggests that fibrous papule of the nose, a lesion of uncertain histogenesis, probably represents a proliferative reactive process consisting mainly of dermal dendritic cells as identified by FXIII-a in most of the lesions. There is some evidence that a small percentage of the dendritic cells may represent involuted naevi and be of melanocytic origin.

The distribution of IgG subclasses in pemphigoid gestationis: PG factor is an IgG1 autoantibody

Using monoclonal antibodies in immunofluorescence techniques, the subclass distribution of anti-basement membrane zone IgG antibodies was studied in the skin, placenta, and serum of patients with pemphigoid (herpes) gestationis. IgG1 was found to be the major IgG subclass in both serum and tissue, being detected in the sera of all pemphigoid gestationis patients studied. In pemphigoid and pemphigus, however, the distribution of IgG subclasses was heterogeneous, with IgG4 being the dominant autoantibody. Pemphigoid (herpes) gestationis factor, the circulating anti-basement membrane zone autoantibody thought to be pathogenic in pemphigoid gestationis, is therefore, an IgG1 antibody, with inferred complement binding capacity. Tissue damage in pemphigoid gestationis is apparently mediated by complement fixation which is detected via the classical complement cascade.

Epithelioid cell histiocytoma: a new entity

This is a report of a previously undescribed type of histiocytoma distinguished clinically by its occurrence as a solitary elevated nodule often with a vascular appearance and cytologically by the presence of large angulated epithelioid cells. Nineteen lesions from 11 women and eight men have been studied. The lower limb was the commonest site for the nodules. The mean age at presentation was 42 years (range 23-63). Only one lesion recurred after attempted removal. This lesion in the past may, have been mistaken for a Spitz naevus. Immunohistochemical findings mirror those of ordinary histiocytomas. In particular approximately 50% of the constituent cells label with a polyclonal antibody directed against factor XIIIa--an antibody that labels dermal fixed connective tissue cells (fibrocytes) and cells in ordinary histiocytoma, but not the cells of Spitz or common melanocytic naevi.

Histiocytoma cutis: a tumour of dermal dendrocytes (dermal dendrocytoma)

The histogenesis of histiocytoma (dermatofibroma) was investigated using new antibodies that demonstrate factor XIIIa (FXIIIa) positive cells and the monocyte macrophage cell series (MAC 387), in formalin fixed tissue. The distribution of S100 protein, vimentin and Ulex europaeus agglutinin I (UEA-I) were also studied. The antibody against FXIIIa labelled the normal dermal population of fixed connective tissue cells (dermal dendrocytes) emphasizing their dendritic processes; cells that are widely distributed, but are most numerous in the papillary dermis. In contrast, the antibody, MAC 387 against monocyte derived macrophages, did not label this cell population. In 30 histiocytomas, intense labelling for FXIIIa was found peripherally, but labelling was rather weaker in cells situated centrally. Only a few cells labelled for S100 protein and with the monoclonal antibody MAC 387, but vimentin positivity was universal. UEA-I labelled only vessels in histiocytomas. However, FXIIIa labelling was negative in 16 dermatofibrosarcomas, three keloids and several other fibroproliferative lesions. These contrasting results with FXIIIa labelling have practical implications for diagnosis of benign and malignant spindle cell tumours of the skin. We conclude that histiocytomas (dermal dendrocytomas) take their origin from dermal fixed connective tissue cells, (dermal dendrocytes), but other spindle cell tumours may differ in histogenesis.

Routine diagnostic immunohistochemical labeling of extracellular antigens in formol saline solution-fixed, paraffin-embedded cutaneous tissue

A technique involving modification of the routine paraffin embedding procedure that allows immunohistochemical examination of extracellular antigens by light microscopy is described. The method is thus suitable for routine diagnostic immunofluorescence studies, permitting reliable, reproducible immunolabeling of immunoglobulins and complement components usually not preserved by routine processing procedures. Immunoreactivity as measured by direct immunofluorescence and immunoenzymatic (peroxidase-antiperoxidase) histochemistry is comparable to results with fresh-frozen cryostat sections. Morphologic preservation is superior, however, and the processed material is suitable for routine hematoxylin-eosin staining.