Monoclonal plasma cell proliferative diseases such as multiple myeloma and plasmacytoma can involve extramedullary sites at the time of first presentation, or subsequently in the course of the disease. Under such circumstances, they can mimic primary or metastatic carcinomas, neuroendocrine or neuroectodermal tumours and lymphomas, and the pathologist often has to resort to immunohistochemistry as an aid to diagnosis. We studied the morphology and immunohistochemical properties of 10 cases of previously confirmed monoclonal plasma cell proliferative lesions retrieved from the files of the Department of Pathology, University of Malaya. Serial 4u thick paraffin sections were stained with H&E, the Unna-Pappenheim technique for nucleic acid and a panel of antibodies using a standard immunoperoxidase technique. Light chain restriction was demonstrable in most of the cases. Seven (70%) showed kappa and 2 (20%) lambda light chain restriction. The remaining case was not stainable with most of the antibodies in the panel. The majority (80%) of cases showed accompanying IgG heavy chain in the cytoplasm, while 1 case had IgA. Seven (70%) showed membrane positivity with antibody to epithelial membrane antigen (EMA) and 7 (70%) cytoplasmic positivity with antibody to vimentin. This study enhances our awareness that neoplastic plasma cells can be positive for EMA and vimentin, and cautions us from misinterpreting these lesions as carcinomas or sarcomas. Notwithstanding that, immunohistochemical staining for kappa and lambda light chains can be helpful in differentiating monoclonal plasma cell proliferations from polyclonal ones.
Two cases of either peripheral odontogenic fibroma (POF) (WHO type) or peripheral ameloblastoma are reported. Their immunohistochemical characteristics were investigated in an attempt to clarify their histogenesis. The results showed that the epithelial component of this neoplasm tended to retain its distinct odontogenic character and expressed a keratin profile different from that of the overlying oral epithelium from which both cases most probably originated. The connective tissue element of these tumors was vimentin-positive and S-100 protein negative, confirming their mesodermal nature but precluding the possibility of ectomesenchymal derivation. No reactivity for desmin was noted.
The lining epithelium of 15 cases of odontogenic keratocyst (OKC) was evaluated immunohistochemically. The peroxidase-antiperoxidase technique was applied to study the distribution of polyclonal keratin and S-100 protein while the indirect method was used to examine monoclonal vimentin and desmin reactivity. Consistent positive keratin staining was revealed in the lining epithelium of all 15 OKCs with additional intense staining in the stratum corneum. None of the cases showed vimentin or desmin reactivity within the lining epithelium elements. One of the 15 cysts studied showed positive S-100 protein staining in the nuclei of the lining epithelial cells. The pertinent literature on the immunophenotyping of the lining epithelium of OKC is reviewed.
Granular cell ameloblastoma (GCA) is a well recognized variant of follicular ameloblastoma with extensive granular cell change. In contrast, plexiform granular cell odontogenic tumor (PGCOT) is a rare and recently described lesion characterized histologically by a monophasic plexiform pattern of granular cells. In this paper, two cases of an unusual granular cell odontogenic tumor exhibiting combined features of these two entities are described along with their immunohistochemical characteristics. The granular cells of both the GCA and PGCOT areas showed similar patterns of expression for keratin and S-100, which differed from those of typical ameloblastoma. No reactivity for desmin or vimentin was noted. The histomorphologic and immunohistochemical features of these hybrid tumors suggest that the granular cells present have a common origin, most probably the odontogenic epithelium.
Seventeen cases of desmoplastic ameloblastoma were examined immunohistochemically. Immunoperoxidase techniques were applied for detection of keratin, desmin, vimentin and S-100 protein expression in these tumors. The tumor epithelium of desmoplastic ameloblastoma exhibited weak, focal, inconstant keratin staining, weak, variable expression of S-100 protein, desmin immunoreactivity of mild to moderate intensity and vimentin non-reactivity. The pertinent literature on the immunohistochemistry of ameloblastomas is briefly reviewed.
Clear cell sarcoma of kidney (CCSK) is a rare but distinct tumor of childhood frequently confused with Wilms' tumor (nephroblastoma). It has a characteristic histology, a marked predilection for metastasis to bone, and an aggressive clinical course with a high relapse rate in spite of surgical excision, chemotherapy and radiotherapy. We report the first histologically proven CCSK in a Malaysian patient. This was an 8-mth-old Malay boy who was clinically diagnosed to have stage I Wilms' tumor. Despite treatment, he developed multiple metastases 10 mths after initial presentation and died soon after. Emphasis is placed on recognizing this entity in view of (1) its naturally aggressive behaviour and (2) the prospect of improving prognosis with currently recommended intensified chemotherapeutic regimes. Its immunohistochemical profile of vimentin-positivity and negativity for epithelial membrane antigen, cytokeratin and Factor-8 related antigen is more in favour of a mesenchymal or glomerular origin than a tubular or vascular origin.
A five-month-old male baby presented with an abdominal mass which was found on computerised tomography (CT) to be involving the left kidney. Nephrectomy and histopathological study showed morphological featues of a malignant rhabdoid tumour. The tumour cells stained strongly for cytokeratin and epithelial membrane antigen and less intensely for vimentin. Electron microscopy revealed concentric whorled arrays of intermediate filaments within the tumour cell cytoplasm. The child was put on post-operative chemotherapy and radiotherapy but developed bilateral lung metastases and died three months after surgery.
The cytological features of a rare case of undifferentiated (embryonal) sarcoma of the liver are presented. The cytology smears showed singly dispersed polygonal and spindle cells as well as loose clusters of cells held together in myxoid material. Neoplastic cells were generally large with round, oval or lobulated nuclei. The cytoplasm was variable in amount with ill-defined borders. Occasional multinucleated cells were also present. Hyaline globules were present on sections of the cell block. Immunohistochemical studies performed showed positivity for vimentin, cytokeratin and alpha-1-antitrypsin (AAT) in the tumour cells.
Tumors of dendritic reticulum cells are rare neoplasms that exhibit significant morphologic overlap with other malignancies. Fine-needle aspiration cytologic appearances of this neoplasm are not well understood. A 33-yr-old woman presented with a rapidly growing nodular mass in the right upper cervical region and right-sided ptosis. Fine-needle aspiration cytology of the mass showed dissociated as well as clustered, large, polygonal cells that showed high nuclear-cytoplasmic ratio. Nuclei were round, oval, or irregular in shape. Large and small blastoid forms with prominent nucleoli and chromatin clumping as well as binucleated cells and cells with lobulated nuclei were seen. Numerous mitoses were observed. The tumor cells expressed focal immunocytochemical reactivity to CD45 and CD68, but were negative for CD2, CD3, CD4, CD8, CD20, CD30, CD45RO, epithelial membrane antigen (EMA), cytokeratin, and HMB45. Histologic sections of the biopsy from the growth showed nodal tissue effaced by a tumor composed of large, pleomorphic neoplastic cells with some binucleate and multinucleate forms resembling Reed-Sternberg cells. The intervening stroma contained numerous small lymphocytes. Tumor cells expressed vimentin, S-100 protein, CD68, and MAC387, but were negative for LCA, CD1a, CD3, CD15, CD20, CD21, CD23, CD30, CD35, carcino-embryonic antigen, HMB45, cytokeratin AE1/3, EMA, myeloperoxidase, lysozyme, smooth-muscle actin, and desmin. The combined histologic and immunohistologic features suggested a histiocytic/dendritic reticulum cell neoplasm and a diagnosis of interdigitating dendritic reticulum cell sarcoma was made.