Malignant histiocytosis. A reassessment of cases previously reported in 1975 based on paraffin section immunophenotyping studies

Cutaneous histiocytic malignancy. Immunohistochemical re-examination of cases previously diagnosed as cutaneous "histiocytic lymphoma" and "malignant histiocytosis"

True histiocytic lymphoma (THL) and malignant histiocytosis (MH) have been defined by clinical and histologic findings and enzyme histochemistry. We reviewed cases previously diagnosed as cutaneous histiocytic lymphoma (HL) and MH with cutaneous lesions. These cases had been classified as "histiocytic" on the basis of previous enzyme histochemistry profiles of frozen tissue. Cutaneous tumor cells were reevaluated using a panel of immunohistochemical stains in formalin-fixed, paraffin-embedded tissue in correlation with histopathologic examination. The antibodies used in this study were directed against CD45 (leukocyte common antigen [LCA]), CD20 (L26) for B cells, CD3 and CD45RO (UCHL-1) for T cells, CD68 (KP-1) and lysozyme for histiocytes, as well as CD30 (BerH2) for Ki-1 positive cells. On re-evaluation, the seven cases originally classified as HL were reclassified as one case of THL with neoplastic cells positive for CD68 (KP-1) and lysozyme, two cases with immunohistochemical features of Ki-l lymphoma (including one of T-cell lineage), three cases of T-cell lymphoma, and one case of B-cell lymphoma, all associated with variable degrees of reactive histiocytosis. The four cases originally classified as MH were reclassified as two cases of MH and two cases of uncertain lineage. Although rare, histiocytic malignancies do exist. However, the diagnosis of histiocytic malignancy should be made only after careful correlation of atypical tumor cells in histopathologic sections and sections stained immunohistochemically. Erroneous classification of reactive histiocytes as neoplastic histiocytes using only enzyme histochemistry in frozen sections is a pitfall to be avoided.

Anaplastic large cell lymphoma with histiocytic phenotypes

A 38 year old man died suddenly of widespread lymphoid neoplasm after a short clinical course. Histologically the tumor was composed of pleomorphic large cells that often demonstrated phagocytic activity. Moreover, histochemical and immunohistochemical tests revealed that the tumor cells had the phenotypes of both anaplastic large cell lymphoma and histiocytic cells. Immunogenotyping failed to demonstrate any lymphoid nature. This case might be categorized as anaplastic large cell lymphoma with histiocytic phenotypes.

Liver changes in reactive haemophagocytic syndrome

Hepatomegaly and deranged liver functions are common findings in reactive haemophagocytic syndrome (RHS). We report the findings of 12 fatal cases of RHS in which histological materials of the liver are available for study. The underlying diseases of these patients included lymphoma/leukaemia (6 cases), disseminated undifferentiated carcinoma of the ovary (1 case), disseminated nasopharyngeal carcinoma complicated by tuberculosis (1 case), adenovirus pneumonia (1 case), pneumococcal pneumonia (1 case), typhoid fever (1 case), and possible drug intoxication (1 case). Ten patients had involvement of the liver by the underlying disease process which contributed to the marked hepatic derangement. Non-specific reactive hepatitis, sinusoidal dilatation and steatosis resulting from systemic or local effects of the associated diseases and the haemophagocytosis also added to the high incidence of liver abnormalities. A diffuse Kupffer cell hyperplasia with haemophagocytosis is characteristic of the syndrome, as all the cases showed increased numbers of bland-looking histiocytes within the hepatic sinusoids and haemophagocytosis which was moderate to marked in 8 cases and mild in 4. Thus the finding of Kupffer cell hyperplasia with prominent haemophagocytosis in liver biopsy is indicative of an element of RHS and warrants clinical monitoring. Differential diagnoses of haemophagocytosis in liver are also discussed.

Histiocytic cytophagic panniculitis: molecular evidence for a clonal T-cell disorder

Histiocytic cytophagic panniculitis is a systemic disease of unknown etiopathogenesis that invariably involves the subcutaneous fat and is histologically characterized by phagocytosis of blood elements by histiocytes that appear to be benign. Immunophenotypic and genotypic studies of biopsy specimens of the lesions of a 58-year-old woman showed that the lymphocytic infiltrates accompanying the histiocytes in the subcutis were composed of clonal T-cells with rearrangement of the surface receptor gene. Our findings suggest that the primary abnormality in histiocytic cytophagic panniculitis may be a clonal T-cell proliferation.

Tumours classified as "malignant histiocytosis" in children are T-cell neoplasms

During the last five years increasing evidence has accumulated that many tumours classified as 'histiocytic' in the past do not originate from macrophages, but from transformed (or anaplastic) large lymphoid cells. Most of these studies have focused upon adult neoplasms. Knowledge concerning the lineage of 'histiocytic' tumours in the paediatric age group is more limited. In this study we have examined the clinical, morphological and immunophenotypical features of six childhood malignancies originally diagnosed as being of histiocytic origin. Three patients showed an aggressive course with involvement of internal organs and very short survival times. Two patients were brought into remission: one is alive without active disease after seven years; the other died after seven years due to treatment-related cardiomyopathy. The remaining patient had a protracted course for two and a half years, but subsequently deteriorated and died three years after diagnosis. The histomorphological features in five cases were those of anaplastic large cell lymphomas. The remaining case consisted of pleomorphic (rather than anaplastic) large lymphoid cells. In all cases the immunophenotypical examination showed features characteristic of activated T lymphocytes. All cases were positive for Ki-1 (CD30), and three were positive for epithelial membrane antigen (EMA). Histiocyte-associated markers were positive in residual reactive macrophages, but nowhere could unequivocal positivity for macrophage-associated markers be seen in the neoplastic cells. It is concluded that most childhood malignancies in the past classified as 'histiocytic' are examples of anaplastic large cell (Ki-1) lymphomas of T-cell type and that true histiocytic malignancies are exceedingly rare in the paediatric age group.

Splenic involvement by aggressive malignant lymphomas of B-cell and T-cell types. A morphologic and immunophenotypic study

To determine whether there are any consistent morphologic differences between B-cell and T-cell aggressive non-Hodgkin's lymphomas of the spleen, the authors analyzed 16 spleens involved by mixed cell (1 case) or large cell (15 cases) lymphomas. Immunologic data were derived from cell suspensions or frozen tissue in each case. Five cases had a T-cell phenotype, and 11 were B-cell. Morphologic features favoring a T-cell phenotype included epithelioid histiocytic reactions, confinement of the lymphomas to the splenic T-zones (periarteriolar lymphoid sheath and marginal zone), and clear cell or polymorphous cytologic features. Features favoring a B-cell phenotype included multiple discrete nodules in the white pulp, large coalescent tumor nodules in association with small lymphocytic lymphoma, and large non-cleaved or immunoblastic plasmacytoid cytologic characteristics. Four cases were unusual because most neoplastic large cells were distributed diffusely or formed only small aggregates in the red pulp without definite tumor masses or nodules involving the white pulp. Because of this distribution and the frequently encountered erythrophagocytosis by benign-appearing histiocytes, these cases resembled malignant histiocytosis. A T-cell phenotype was predicted for all four cases; however, only one case, a lymphoma with polymorphous cytologic characteristics, was of T-cell lineage. The other three cases were of B-cell lineage. The authors' results indicate that in most instances the B-cell or T-cell nature of aggressive splenic lymphomas is predictable from the distributional and cytologic features. As in lymph nodes, there are cases for which the morphologic characteristics of B-cell and T-cell lymphomas are indistinguishable.

KP1 (CD 68) staining of malignant melanomas

The monoclonal antibody KP1, which recognizes the CD 68 antigen on macrophages and myeloid precursors, was tested on 28 malignant (primary and metastatic) melanomas, 28 naevi, and 17 skin biopsies showing either normal (10) or hyperplastic melanocytes (7). Sixteen of 20 primary melanomas and six of eight metastatic melanomas showed variable numbers of KP1 positive tumour cells. All but five benign melanocytic proliferations (two Spitz naevi and three intradermal naevi), as well as normal and hyperplastic melanocytes were negative. These results indicate that difficulties may occur with the use of KP1 in the differential diagnosis between melanomas and neoplasms derived from histiocytes-macrophages, and that the expression of CD 68 antigen might be related to tumour progression in melanocytic cells.

Cutaneous lymphomas of phenotypically undetermined lineage: contribution of genotypic analysis

Genotypic analyses were performed in six primary cutaneous lymphomas whose lineage could not be assessed on the basis of histologic and phenotypic data. By immunophenotyping, these neoplasms expressed leukocyte common antigen and HLA-DR but did not show consistent immunostaining for B-cell or T-cell differentiation antigens. Expression of nonspecific histiocytic markers such as lysozyme and alpha 1-antitrypsin was found in three cases. By genotyping, three cases retained a germline configuration and immunoglobulin gene rearrangement was observed in one case, T-cell receptor gene rearrangement was found in one case, and both types of rearrangements in one case. Of the three patients in whom gene rearrangements were noted, two rapidly died and the other patient, with a dual genotype, is still alive 15 years after diagnosis. The three patients without gene rearrangements are alive and well after a mean follow-up of 2.5 years. It appears that cutaneous lymphomas with an uncertain phenotype include at least some cases of authentic B-cell or T-cell lymphomas. The germline configuration that we observed in cases with a chronic course remains difficult to explain. It may be related to a low malignancy form of histiocytic lymphoma, an atypical polyclonal hyperplasia, or even a low-grade lymphoma arising from a primitive cell without established commitment to either B- or T-cell lineage.

Anaplastic large cell Ki-1 lymphoma involving bone marrow: marrow findings and association with reactive hemophagocytosis

This report describes the bone marrow findings in four patients whose marrow was involved by anaplastic large-cell Ki-1 lymphoma, an uncommon event in this type of lymphoma. In the marrow aspirate smears, the involvement was subtle, and was in the form of isolated large cells with irregular nuclear configuration, coarse chromatin, prominent nucleoli, and basophilic cytoplasm which might be vacuolated. One case showed paradoxically massive involvement in the trephine biopsy taken from the same site as the marrow aspirate. Reactive histiocytic proliferation with hemophagocytosis was also present. Since marrow aspirate or biopsy may be the first pathologic specimen examined in patients having anaplastic large-cell Ki-1 lymphoma, it is important to be able to recognize the small population of neoplastic cells, which should lead to prompt treatment or further investigations as deemed necessary.