T-zone lymphoma (TZL) is a rare subtype of nodal peripheral T-cell lymphoma characterized by a clonal expansion of T-zone lymphocytes accompanied by a proliferation of other T-zone constituents. Non-specific cutaneous alterations are seen in about one-third of all cases, but specific cutaneous involvement is extremely rare. We present a case of TZL with secondary skin infiltration, review the literature on cutaneous manifestations of TZL and discuss the differential diagnosis of TZL.

s From The 18Th Colloquium Of The International Society Of Dermatopathology (Isd) And The Austrian Society Of Dermatopathology

We report on two cases of low grade follicle centre cell lymphoma with a pronounced parafollicular monocytoid/marginal zone B‐cell component. One patient had a history of preceeding follicular high grade B‐cell lymphoma of centroblastic type showing the same light chain restriction and identical immunoglobulin heavy chain gene rearrangement as the low grade lymphoma diagnosed 15 months later. Morphologically, in both cases the two constituents of the low grade tumours were clearly distinguishable. Immunohistochemically, the follicular component strongly expressed bcl‐2 protein in contrast to a weak staining of the marginal zone B‐cell component. Performing PCR, a rearrangement of the major breakpoint region of bcl‐2 was not found. Identical light chain restriction of the follicular and the monocytoid B‐cell/marginal zone components strongly indicates a clonal relationship between them. A monocytoid/marginal zone B‐cell component in follicular lymphoma probably results from differentiation of the follicle centre cells and does not indicate a composite lymphoma.

Twenty cases of cutaneous follicular lymphoid hyperplasia with monotypic plasma cells are presented in a clinicopathologic study on 18 patients. The plaque-like or nodular lesions were solitary in 10 and multiple in eight patients. Immunohistochemistry showed well-defined B- and T-cell areas. Sheets of monotypic plasma cells occurred either interfollicularly or adjacent to the sclerotic stroma, with expression of IgG/kappa in 14 and IgG/lambda in six cases. In one patient with multiple lesions, one sample contained polyclonal plasma cells, whereas the other specimen showed light chain restriction. In another patient, disease recurred with a polytypic cutaneous plasma cell infiltrate. Polymerase chain reaction (PCR) revealed clonal immunoglobulin heavy chain gene rearrangements in eight of 13 cases, which was confirmed by Southern blot analysis in three samples. Clonal T-cell receptor chain gene rearrangements were not detected. Disease progression to overt malignant lymphoma did not occur within the follow-up period of up to 12 years, but recurrent disease was seen in three patients. Our data indicate that cutaneous lymphoid hyperplasia with monotypic plasma cells is a biologically distinct clinicopathological entity.

Four mucinous sweat gland carcinomas were examined for the distribution of cytokeratin (CK) polypeptides using immunohistochemical techniques on paraffin‐embedded sections. All the tumour specimens reacted with monoclonal antibodies to CK 7, CK 8, CK 18 and CK 19. Antibodies to CK 1, CK 1/2/10/14, CK 1/5/10/11, CK 13, CK 14 and CK 20 did not stain any of the carcinomas. The results add additional support to the notion that mucinous sweat gland carcinoma represents a tumour histogenetically related to the eccrine secretory coil. Furthermore, the absence of CK 20 might significantly contribute to the differentiation of this tumour from cutaneous metastases from gastrointestinal carcinomas.

Signet-ring cell melanoma is a rare morphologic variant of malignant melanoma. We describe a 27-year-old man with widespread cutaneous and internal metastases of an unknown primary tumor. One skin biopsy specimen and a fine-needle aspirate showed polygonal tumor cells consistent with the diagnosis of metastatic melanoma, but a second skin biopsy specimen revealed neoplastic cells with a signet-ring cell appearance. Both specimens, however, yielded identical immunohistochemical findings. Tumor cells were positive for vimentin and S-100 protein and reacted with the melanoma markers HMB-45 and NKI-C3. Ultrastructural studies revealed abundant intermediate filaments in the cytoplasm of the signet-ring cells. Based on these findings, a diagnosis of metastatic melanoma was made. In this report we describe the fourth case of metastatic signet-ring cell melanoma, and discuss how malignant melanoma may lead to metastases that have divergent morphologic appearances in the same patient.

In this study 15 eccrine poromas were analysed clinically, histologically and immunohistologically. They were all solitary lesions, showing a predilection for the head and neck. In none of the tumours was diagnosis possible on the basis of clinical examination. Histomorphologically, eccrine poromas were characterized by aggregations of neoplastic cells continuous with the epidermis. The neoplasms consisted of two cell types, poroid and cuticular. Poroid cells predominated, while cuticular cells were only found in small foci, sometimes showing tubular differentiation. Immunohistologically, most of the tumour cells showed a cytokeratin pattern (CK1, 5, 10, 11+, CK1-19+) favouring differentiation toward the abluminal cell of the dermal eccrine duct rather than toward the abluminal cell of the intraepidermal segment of the eccrine duct. Only a small proportion of cells revealed the immunohistological features of the abluminal cell of the intraepidermal duct (CK1+, CK1, 5, 10, 11+, CK1-19+). In addition, cuticular cells showed differentiation toward the luminal cell of the eccrine duct (CK19+, CK1, 5, 10, 11+, CK1-19+). Simple-type cytokeratins such as CK7 and CK18 were not expressed. In conclusion, our findings favour the hypothesis that ascribes the origin of eccrine poroma to a pluripotential stem cell of the transitional zone between the dermal and the intraepidermal segments of the eccrine duct.

In a 59-year-old patient presenting in October 1981 with pancytopenia, hairy cell leukemia was diagnosed. Splenectomy, followed by treatments with oncovin, lithium, and prednisone were essentially without effect. Up to July 1984 the patient had been regularly transfused with a total of 62 unit. In June 1984 he acquired a transfusion associated hepatitis C which followed a chronic course and resulted in biopsy proven cirrhosis in 1989. The patient became independent of transfusions in July 1984. Repeated blood counts have shown a complete hematologic remission which has now lasted nearly 6 years, whereas focal leukemic infiltrates have persisted in the bone marrow. The patient has tolerated 20 courses of erythropheresis performed because of biopsy proven severe hepatic siderosis without a fall in hemoglobin. It is suggested that the spontaneous long-lasting hematologic remission of hairy cell leukemia is due to endogenous interferon produced in the course of chronic hepatitis C. Low serum levels of interferon-alpha and -gamma were detected.

In a 59-year-old patient presenting in October 1981 with pancytopenia, hairy cell leukemia was diagnosed. Splenectomy, followed by treatments with oncovin, lithium, and prednisone were essentially without effect. Up to July 1984 the patient had been regularly transfused with a total of 62 units. In June 1984 he acquired a transfusion associated hepatitis C which followed a chronic course and resulted in biopsy proven cirrhosis in 1989. The patient became independent of transfusions in July 1984. Repeated blood counts have shown a complete hematologic remission which has now lasted nearly 6 years, whereas focal leukemic infiltrates have persisted in the bone marrow. The patient has tolerated 20 courses of erythropheresis performed because of biopsy proven severe hepatic siderosis without a fall in hemoglobin. It is suggested that the spontaneous long-lasting hematologic remission of hairy cell leukemia is due to endogenous interferon produced in the course of chronic hepatitis C. Low serum levels of interferon-alpha and -gamma were detected.

Well-defined clusters of plasmacytoid T cells were identified in two cases of lymphoid hyperplasia of the skin. With the use of paraffin-embedded and frozen sections and 46 different antibodies, the antigenic profile of plasmacytoid T cells was obtained. Corresponding to plasmacytoid T cells in reactive and neoplastic lymph node conditions, plasmacytoid T cells of the skin were devoid of most T-cell-restricted differentiation antigens CD2, CD3, CD5, and CD8 while expressing monocyte/macrophage-related antigens recognized by Ki-M6 and Ki-M7. In addition, plasmacytoid T cells were positive for CD4, CD45, HLA class II antigens (HLA-DR, Leu-10, MB3, LN2, LN3) and the transferrin receptor. Furthermore, they reacted with anti-Leu-8, MB1, Ki-B3 (CD45R), and MT1. Thus plasma-cytoid T cells are considered to be mononuclear cells with monocyte/macrophage differentiation rather than T lymphocytes. In addition, our findings substantiate the concept that plasmacytoid T cells may function as a hitherto unrecognized subgroup of antigen-presenting cells in the skin.

We report the case of a spontaneously regressing lymphocytic lesion on the neck of a 76-year-old man. Routine histopathological examination revealed a heterogeneous infiltrate composed of both lymphoid follicles and preferentially perifollicular and interfollicular sheets of large atypical cells. Immunohistologically, large atypical cells were positive for Ki-1/Ber-H2 (CD30), anti-Il-2 (CD25), Ber T9, anti-HLA-DR, Leu-5b (CD2), T3 (CD3), Leu-3 (CD4), Leu-1 (CD5) and, occasionally, Leu-M1 (CD15); that is, they showed an arrangement and immunophenotype similar to those of perifollicular Ki-1 positive cells in reactive lymphoid tissue. In contrast, antibodies To15 (CD22), anti-immunoglobulins, and anti-CALLA (CD10) stained polyclonal B-cells restricted to lymphoid follicles and small clusters representing remnants of follicles. We suggest that this lesion be termed "follicular lymphoid hyperplasia of the skin with high content of activated T-helper cells."

The association of primary salivary gland non-Hodgkin's lymphoma (NHL) and immunosialadenitis (myoepithelial sialadenitis, MESA) is well recognized. Within MESA the whole spectrum of lymphoproliferation starting with a prelymphoma transforming into an early lymphoma and later on into a manifest lymphoma can be observed. These lymphomas represent so-called low grade B-cell lymphomas of mucosa associated lymphoid tissue (MALT), an entity also including lymphoplasmocytoid immunocytoma according to the Kiel classification of NHL. In a few patients a transition into a high grade B-cell lymphoma may occur. The recognition of early stages of lymphomas and their distinction from reactive MESA is only possible by application of immunohistological methods.

We have studied 12 cases of cutaneous atypical fibroxanthoma using immunohistochemistry to demonstrate lysozyme, α-1-antitrypsin, S-100-protein, receptors for peanut agglutinin, and intermediate filaments. Results were compared with immunostaining in 24 cases of other so-called fibrohistiocytic tumours. In addition 2 cases of atypical fibroxanthoma and 6 cases of fibrohistiocytic tumours were stained by monoclonal antibodies specific for the monocyte cell lineage (Ki-Ml, Ki-M2, Ki-M6, Ki-M7, Ki-M8, OKM-l and Leu-M1) and double-stained by monocyte-markers and Ki-67.

The case is reported of a 73-year-old man presenting with a history arthralgia, conjunctivitis, fever and typical lesions of acute febrile neutrophilic dermatosis (Sweet's syndrome). Due to massive leukocytosis, an unclassifiable myeloproliferative disorder was later diagnosed. The disease responded well to hydroxyurea but only partly to steroids. The case demonstrates the necessity of close hematologic follow-up in Sweet's syndrome, since some 10% of patients develop hematologic malignancies weeks or months later.

No exact information exists on the diagnostic value of immunohistochemistry applied to the routine material of an institute of surgical pathology. For this reason 390 cases additionally investigated by immunohistochemistry were analyzed retrospectively. This method was applied to 0.5% of all biopsies studied morphologically. On average 4.4 antisera per case were used. 352 cases (90.3%) initially diagnosed by morphology alone (16 benign lesions of debatable type, 111 lesions not clearly defined as benign or malignant, 225 malignant tumours of unknown subtype) could be clarified by immunohistochemistry. To obtain reliable results specific application of immunohistology and a clearcut formulation of the question are necessary. If these criteria are fulfilled immunohistochemistry represents a powerful tool in surgical pathology.