Antibody probes in the diagnosis of anaplastic tumours. I. Malignant round cell tumours

Microwave fixation and rapid processing in a large throughput histopathology laboratory

Technical details of a method of microwave fixation and rapid processing are described. Fresh biopsy specimens are sampled and trimmed into 2 mm thick blocks and irradiated to a temperature of 68 degrees C. They are then processed through cycles of absolute alcohol (75 min), xylene (50 min) and wax (50 min). It is possible, in this manner, to run several 'short' cycles of about 3 hrs each during the working day so that stained sections are available on the same day as receipt of the specimens. Endoscopic biopsies are processed through a shorter cycle comprising 30 min of absolute alcohol (4 changes), 20 min of xylene (3 changes) and 20 min of wax (2 changes). For convenience we also employ an overnight cycle whereby microwave-fixed blocks are processed through several changes of absolute alcohol, xylene and wax without the use of formalin. This method of processing not only removes the use of noxious and potentially toxic formalin but also allows rapid preparation of good quality diagnostic sections with superior antigen preservation compared to formaldehyde fixation.

Alveolar rhabdomyosarcoma metastatic to the ovary. A report of two cases and a discussion of the differential diagnosis of small cell malignant tumors of the ovary

Two young women with alveolar rhabdomyosarcoma metastatic to the ovary are reported. In each case, the ovarian involvement was detected within a few weeks of the discovery of a soft tissue mass by the patient. Symptoms attributable to the ovarian tumor dominated the initial clinical picture in one case. In the other case, the soft tissue mass was not appreciated by the treating physicians until after the diagnosis of rhabdomyosarcoma had been established by examination of the ovarian tumor. The ovarian tumor was unilateral in one case and bilateral in the other. One primary site was the right foot and the other primary site was the left forearm. These cases illustrate that metastatic alveolar rhabdomyosarcoma rarely enters into the differential diagnosis of a small cell malignant tumor of the ovary. Both patients experienced progression of their disease and died, despite aggressive chemotherapy, within 1 year of presentation.

Cutaneous plasmacytomas in dogs: a morphologic and immunohistochemical study

Forty-nine cutaneous plasmacytomas in 46 dogs were studied. Tumors occurred at solitary sites in middle-aged to old dogs (mean age, 9.7 years) and most commonly involved the skin of the digits, lips, and ears. Initial diagnosis was made on the basis of light microscopic morphologic findings. Tumors were graded according to the extent of cellular differentiation and immunoreactivity to a panel of immunohistochemical markers (cytokeratins, canine IgG F[ab]2, neurofilament, neuron-specific enolase, S-100 protein, and vimentin). Immunoreactivity was limited to antibodies directed at canine IgG F(ab)2 and vimentin. Vimentin immunoreactivity was usually greater than that of canine IgG F(ab)2, but there was no correlation between immunoreactivity and histologic grade of the tumors. Thirty-six of 39 dogs (92.3%) followed (mean follow-up, 13 months) were cured by surgical excision. The results of this study indicate that canine cutaneous plasmacytomas are benign neoplasms that should be included in the differential diagnosis of cutaneous round cell tumors in dogs.

Immunoperoxidase staining in the detection of lymph node metastases in stage I breast cancer

Axillary lymph node involvement by tumour metastasis is of major prognostic significance in breast carcinoma. In an immunocytochemical study using monoclonal antibodies to cytokeratins, 7 (23%) of 30 cases of node-negative breast carcinoma were found to contain metastases, resulting in upstaging of the disease. The metastatic foci were missed on routine screening of H&E stained sections. There was no significant association between the presence of metastases and the location, diameter, type or grade of the primary tumour. These findings emphasize the contribution of immunocytochemical staining for the identification and detection of metastatic breast carcinoma in axillary lymph nodes.

Supratentorial neurofibroma unassociated with cranial nerves

A rare case of a solitary neurofibroma occurring in a 42-year old female is described. It was attached to the lateral wall of the cavernous sinus. The literature of previously described intracranial nerve sheath tumours not obviously associated with cranial nerves is briefly reviewed.

The contribution of immunohistochemical staining in tumour diagnosis

With the increasing use of immunohistochemical stains in the diagnostic laboratory, it becomes relevant to review the contributions of this new technology in the area of tumour diagnosis. During 1986, our laboratory received 21,479 biopsy specimens of which 2013 were tumours. Nine hundred and fifty-eight tumours (47.5%) were subjected to immunohistochemical analysis. The biopsy and immunohistochemistry reports of 200 consecutive tumours, including 41 consultation cases, were retrospectively reviewed and assigned to one of the five categories. Immunohistochemical stains confirmed the preferred H & E diagnosis in 106 cases (53%); made the definitive diagnosis from a list of differential diagnosis in 29 cases (14.5%); provided contributory information in 36 cases (18%); were non-contributory in 27 cases (13.5%); and rendered an unsuspected diagnosis in two cases (1%). Immunohistochemical stains were particularly useful in distinguishing between malignant lymphoma and anaplastic carcinoma and in the identification of amelanotic melanoma. The application of a panel of antibodies chosen in accordance with the differential diagnoses considered was very useful in the typing of anaplastic round cell and spindle cell tumours. In 27 cases (13.5%), immunohistochemical stains were non-contributory. About half of these were referred cases and the failure to demonstrate the relevant antigens in normal tissues which served as in-built controls suggested that part of the problem may be due to differences in methods of fixation which led to sub-optimal preservation of tissue antigens. We conclude that immunohistochemical stains provide important and sometimes essential information for definitive typing of anaplastic tumours. Often the information derived was of therapeutic and prognostic relevance. We argue that this is a cost-effective test although we would caution that in all circumstances the interpretation of immunostaining must be made in the context of the histological as well as the clinical and laboratory data.

The application of the avidin-biotin technique to previously stained histological sections

Using the sensitive avidin-biotin peroxidase technique, a wide variety of tissue antigens can be detected in standard histological sections of both normal and pathological tissues previously stained with hematoxylin and eosin. There appears to be no detectable reduction of sensitivity with this method of "restaining" compared to the standard immunoperoxidase procedure applied to unstained tissue sections. This technique makes it possible for retrospective identification of tissue antigens when insufficient unstained material is available.

Atypical fibroxanthoma of the skin: a clinicopathological and immunohistochemical study and a discussion of its histogenesis

The morphological and immunohistochemical characteristics of 37 atypical fibroxanthomas of the skin were examined. Twenty-four tumours were nodular ulcerative lesions on the head and face of patients with a median age of 75 years, whereas 13 tumours occurred on the trunk and limbs of patients with a median age of 48 years. Both pleomorphic polygonal and giant cells as well as the spindle cell component of the tumours stained for the histiocytic markers alpha 1-antichymotrypsin, alpha 1-antitrypsin, lysozyme and, less frequently, for ferritin. Leu M1 antigen and peanut agglutinin receptors were not demonstrable in tumour cells. This antigenic profile was contrasted with the findings in six cases of dermatofibroma which were largely not reactive with the antisera used. The immunohistochemical findings in atypical fibroxanthomas suggest that they represent a homogeneous group of tumours which are related to tissue histiocytes. These results are discussed in the context of the published findings in other so-called fibrohistiocytic tumours including dermatofibrosarcoma protuberans and malignant fibrous histiocytoma. The diagnoses in three cases coded as atypical fibroxanthomas were revised on the basis of their showing a different immunohistochemical profile.

Neuron-specific enolase and malignant lymphomas (23 cases)

The immunoreactivity of polyclonal antiserum to neuron-specific enolase (NSE) has been investigated. Twenty-three cases of malignant lymphoma (ML) were studied and compared with previously published reports. In our study 11 out of 23 cases showed strong or weak NSE positivity; any type of ML could be positive or negative even among B or T cell ML. This study indicated that polyclonal NSE is not a specific marker; it might be an inconstant marker of ML with no apparent correlation between reactivity and morphology or phenotype.

Criteria for the diagnosis of primary endocrine carcinoma of the skin (Merkel cell carcinoma). A histological, immunohistochemical and ultrastructural study of 13 cases

Thirteen cases of primary endocrine carcinoma of the skin (Merkel cell carcinoma) were reviewed with the aim of defining the morphological, immunohistochemical and ultrastructural criteria for diagnosis. The tumour cells were characterized by their scanty cytoplasm, generally small uniform nuclei with finely dispersed chromatin and multiple small nucleoli. Nuclear shapes varied from round to spindle, with larger and pleomorphic forms predominating in 2 tumours. A striking feature seen in 12 tumours was the occurrence of a "ball-in-mitt" pattern represented by 1 or 2 crescentic tumour cells closely wrapped around an oval cell. Staining for neuron-specific enolase was the most consistent marker of the tumour and the characteristic juxtanuclear globular staining for keratin and cytokeratin and the occasional coexpression of neurofilament set this tumour apart from other cutaneous neoplasms, in particular, metastatic carcinoid tumours and oat cell carcinoma from the lung. The fine structural features of note were striking paranuclear or juxtanuclear whorls of intermediate filaments, seen in 7 cases, the presence of variable numbers of membrane-bound dense core granules of 80-150 nm diameter in all cases and cytoplasmic spinous or microvillous projections containing microfilaments in 4 cases. Less consistent characteristics of primary endocrine carcinomas of the skin included cell moulding, argyrophilia and immunohistochemical staining for ACTH, VIP and calcitonin. The high frequency of vessel invasion in this series is in keeping with the high rate of local recurrence, lymph node metastases and visceral dissemination reported. The distinction from other similar appearing tumours in the skin is discussed.