HMB-45 staining for cytology of primary melanoma of the vagina. A case report

BACKGROUND: Malignant melanoma in the vagina is very rare, but its diagnosis is usually easy if a melanin pigment is present. With cytodiagnosis, however, it is difficult to differentiate amelanotic melanoma or scantily pigmented melanoma from other conditions. In the present case, monoclonal antibody HMB-45, the efficacy of which has been established in histologic studies, was used in the cytodiagnosis of amelanotic melanoma in the vagina. CASE: A woman, aged 78 years, presented with a brownish, nodular tumor, diameter 3 cm, in the vagina. Scraping smears with Papanicolaou staining showed nonepithelial malignant cells without granules suggesting melanin. Smears stained with HMB-45 showed positive immunoreactivity. The diagnosis underwent histologic confirmation of amelanotic melanoma on the initial biopsy. CONCLUSION: Cytodiagnosis was made with HMB-45, which proved very effective in the differential cytodiagnosis of amelanotic melanoma and scantily pigmented melanoma, particularly because it obviated the need for tissue invasion.     

Melanoma metastatic to the breast: utility of fine needle aspiration and immunohistochemistry

OBJECTIVE: To describe the morphologic spectrum of metastatic malignant melanoma (MM) cells involving the breast and to explore the diagnostic utility of HMB45, Mart-1, Melan-A and T311 (antityrosinase) antibodies in fine needle aspiration material of MM metastatic to the breast. STUDY DESIGN: Cytologic material from 21 cases (18 women) was reviewed for cytomorphology (epithelioid, spindled, mixed) and immunocytochemical staining attributes for Mart-1, HMB45, T311, Melan-A and cytokeratin based on tissue availability. RESULTS: Seventeen cases (81%) demonstrated epithelioid cell morphology, with 14% exhibiting mixed and 5% spindled morphologies. All 21 cases (100%) were immunoreactive with Mart-1 antibody, with 81% (17/21) immunoreactive for HMB45. In 38% of cases there was a similar percentage of cells immunoreactive for Mart-1 and HMB45, while 48% showed a higher percentage of cells immunoreactive for MART-1 than HMB45. Immunoreactivity with T311 was seen in 8 of 11 cases tested (73%). All six cases tested (100%) were immunoreactive with Melan-A. Staining for cytokeratin was negative in all eight cases tested. CONCLUSION: Because the majority of MM metastatic to the breast shows epithelioid cell morphology, it may mimic primary breast carcinoma. Mart-1 should be part of the immunocytochemical panel utilized to confirm the diagnosis of MM metastatic to the breast.     

Comparative Histopathology of Grey‐Horse‐Melanoma and Human Malignant Melanoma

Equine melanoma shows striking features particularly with regard to clinical development in grey horses: in contrast to malignant melanoma in humans and in solid coloured horses that are characterized by early onset of metastasis, pigment cell tumours display almost benign clinical features in ageing grey horses. Through evolution, grey horses appear to be in a favourable position in regard to the biological behaviour of melanomas. Yet unknown factors inhibiting or retarding early melanoma metastasis may be responsible for this phenomenon. In this study, immunostaining profiles and histopathologic patterns of equine vs. human melanotic tumours were compared. In addition, the expression of melanoma markers currently used in human melanoma detection and characterization were evaluated for their applicability in equine melanoma diagnosis. Immunohistopathologic investigations revealed that benign grey horse melanomas share common features with human blue nevi and with human malignant desmoplastic melanomas, whereas their resemblance to other types of human cutaneous malignant melanomas is less pronounced. Our data equally underline that S‐100, proliferating cell nuclear antigen (PCNA), HMB‐45, Ki‐67, T‐311 and CD44 can serve as reliable markers for horse melanomas. Further investigations aiming at identifying factors retarding metastasis in affected grey horses are needed, as they may contribute to the development of novel treatment strategies for human malignant melanoma.     

Characterization of monoclonal antibody 155.8 and partial characterization of its proteoglycan antigen on human melanoma cells

Immunization of mice with a plasma membrane-enriched fraction from human malignant melanoma cells and subsequent generation of hybridomas resulted in the isolation of an IgG1 monoclonal antibody, 155.8, that recognizes chondroitin sulfate proteoglycans. By cell binding analysis, 155.8 was shown to react with seven of eight cultured melanoma cell lines, but not with a variety of lymphoblastoid cell lines or cultured tumor cells derived from other solid tumor types. Indirect immunoprecipitation of the 155.8 antigen from intrinsically labeled melanoma cells revealed a glycoprotein of Mr = 250,000 and a sulfated molecule of Mr greater than 400,000. The antigen was identified as a chondroitin sulfate type A/C proteoglycan synthesized by melanoma cells on the basis of its sensitivity to chondroitinase ABC digestion and the identification of sulfated glycosaminoglycans released from the antigen immunoprecipitated by 155.8. The determinants recognized by antibodies 155.8 and 9.2.27, another anti-chondroitin sulfate proteoglycan, immunoprecipitate only a proteoglycan from high density cesium chloride gradient fractions, (1.487 g/liter); however, they immunoprecipitate a free glycoprotein of Mr = 250,000 from low density fractions (1.317 g/liter). This demonstrated that the 155.8 and 9.2.27 determinants, both of which reside on the glycoprotein of Mr = 250,000, are also present in the proteoglycan, suggesting that this glycoprotein is the proteoglycan core protein. Monoclonal antibody 155.8 reacts with a determinant on the core protein distinct from that recognized by 9.2.27. Proteoglycans bearing 155.8 determinants are distributed on the surface of cultured melanoma cells in a punctated fashion that apparently resolves to short, filamentous structures at high magnification. Immunohistochemical analysis demonstrated that 155.8-defined proteoglycans are found in freshly biopsied melanoma tissue, suggesting that these antigens are also synthesized in vivo by melanoma cells.     

Comparison of immunohistochemical labelling of melanocyte differentiation antibodies melan-A, tyrosinase and HMB 45 with NKIC3 and S100 protein in the evaluation of benign naevi and malignant melanoma

A panel of three melanocyte differentiation antibodies has been compared with anti-S100 protein and NKIC3 in an assessment of benign and malignant melanocytic lesions.Anti-polyclonal S100 protein labelled all cases of primary cutaneous malignant melanoma, metastatic melanoma, desmoplastic melanoma and myxoid melanomas. In addition all benign and dysplastic naevi were positive. Conversely, HMB 45 was the least sensitive marker, labelling 24/31 primary cutaneous melanomas, 14/24 metastatic melanomas and only 1/6 desmoplastic melanomas. In the case of naevi, only junctional forms labelled consistently. Results for anti-melan-A and anti-tyrosinase were similar, although anti-tyrosinase proved slightly more sensitive in cases of malignant melanoma. NKIC3 revealed similar results to anti-tyrosinase, but had the disadvantage of reduced selectivity.It is concluded that anti-tyrosinase and anti-melan-A are useful additions to the panel of melanocytic monoclonal antibodies. In addition, both antibodies appear to have greater sensitivity for malignant melanoma than the conventionally used HMB 45 and could be considered as supportive markers to polyclonal anti-S100 protein in the diagnosis of malignant melanoma.     

Cytologic detection of penile malignant melanoma of soft parts in pleural effusion using monoclonal antibody HMB-45

A case of penile malignant melanoma of soft parts ("clear cell sarcoma") with pulmonary metastases and malignant effusions is reported. The tumor cells in the pleural effusion were scattered singly and admixed with reactive mesothelial cells. They had abundant granular cytoplasm and round nuclei with prominent nucleoli. Although staining for S-100 protein was positive in sections from the penile lesion, it was negative in sections of a cell block prepared from the effusion; however, the effusion tumor cells demonstrated immunoreactivity with HMB-45, an antimelanoma monoclonal antibody.     

鉴别无色素性恶性黑色素瘤方法的探讨

无色素及少色素性恶黑鉴别诊断时,（１）组织化学铁反应,褪色素和黑色素银染对证实瘤细胞中黑色素是有帮助的,但不能从无色素性恶黑中检出黑色素。因此对无黑色素恶黑的诊断和鉴别诊断帮助不大。网状纤维染色良性病均有增加,而恶黑几乎没有增加或仅极少增加。因此网状纤维染色有助于良恶性的鉴别。（２）免疫组化Ｓ－１００１８例恶黑及６例良性痣均显示阳性,这对无色素恶黑的诊断是有价值的,但对色素痣的恶变帮助不大。１６例恶黑中１４例色素性与１０例无色素性恶黑ＨＭＢ４５均显示阳性,证明两者有共同抗原,总阳性率８７．５％,６例良性痣均为阴性,证明无ＨＭＢ４５抗原。结果提示ＨＭＢ４５免疫组化检测不仅对无色素及少色素性恶黑的诊断与鉴别诊断实用性大,还可以用于对恶黑与良性痣、良性痣恶变的鉴别。（３）本组４例无色素性恶黑电镜下均找到前黑色素小体。因此在其他方法诊断困难时,应用电镜检查对确诊具有决定性作用。     

Islet cell antigens and autoantigen(s): Monoclonal antibodies and further characterization

A novel series of murine monoclonal antibodies to islet cells (1–45, 1–51, 1–52 and 1–39) have been generated using human insulinoma homogenate as the immunogen in order to characterize pathogenetically relevant islet cell autoantigen(s). Differentiation antigens recognized by these islet cell monoclonal antibodies displayed varied cytological distribution (pan-islet or peripheral mantle only). Monoclonal antibody 1–45 reacted with all endocrine subsets of the pancreatic islet, similar to the reactivity of islet cell autoantibody positive sera from type I diabetes subjects. Preexposure to pH2 abolished the immunoreactivity of the autoantigen; 1–45 antigen was also sensitive to low pH. Preexposure to 100° C for 1 h did not significantly alter the immunoreactivity of islet antigens recognized by ICAb positive patient sera and monoclonal antibody 1–39, thus demonstrating the extraordinary heat stability of the corresponding epitopes; those recognized by 1–45 were less heat stable. Islet cells were found to share 1–45 differentiation antigen(s)/epitope(s) with other neuroendocrine cells,viz. amerior pituitary, adrenal medulla and gut endocrine cells.     

The usefulness of c-Kit in the immunohistochemical assessment of melanocytic lesions

C-Kit (CD117), the receptor for the stem cell factor, a growth factor for melanocyte migration and proliferation, has shown differential immunostaining in various benign and malignant melanocytic lesions. The purpose of this study is to compare c-Kit immunostaining in benign nevi and in primary and metastatic malignant melanomas, to determine whether c-Kit can aid in the differential diagnosis of these lesions. c-Kit immunostaining was performed in 60 cases of pigmented lesions, including 39 benign nevi (5 blue nevi, 5 intradermal nevi, 3 junctional nevi, 15 cases of primary compound nevus, 11 cases of Spitz nevus), 18 cases of primary malignant melanoma and 3 cases of metastatic melanoma. The vast majority of nevi and melanomas examined in this study were positive for c-Kit, with minimal differences between benign and malignant lesions. C-Kit cytoplasmatic immunoreactivity in the intraepidermal proliferating nevus cells, was detected in benign pigmented lesions as well as in malignant melanoma, increasing with the age of patients (P=0.007) in both groups. The patient's age at presentation appeared to be the variable able to cluster benign and malignant pigmented lesions. The percentage of c-Kit positive intraepidermal nevus cells was better associated with age despite other variables (P=0.014). The intensity and percentage of c-Kit positivity in the proliferating nevus cells in the dermis was significantly increased in malignant melanocytic lesions (P=0.015 and P=0.008) compared to benign lesions (compound melanocytic nevi, Spitz nevi, intradermal nevi, blue nevi). Immunostaning for c-Kit in metastatic melanomas was negative. Interestingly in two cases of melanoma occurring on a pre-existent nevus, the melanoma tumor cells showed strong cytoplasmatic and membranous positivity for c-kit, in contrast with the absence of any immunoreactivity in pre-existent intradermal nevus cells. C-Kit does not appear to be a strong immunohistochemical marker for distinguishing melanoma from melanocytic nevi, if we consider c-Kit expression in intraepidermal proliferating cells. The c-Kit expression in proliferating melanocytes in the dermis could help in the differential diagnosis between a superficial spreading melanoma (with dermis invasion) and a compound nevus or an intradermal nevus. Finally, c-Kit could be a good diagnostic tool for distinguishing benign compound nevi from malignant melanocytic lesions with dermis invasion and to differentiate metastatic melanoma from primary melanoma.     

A monoclonal antibody recognizes an O-acylated sialic acid in a human melanoma-associated ganglioside

Monoclonal antibody D1.1 originally prepared against the B49 cell line derived from a rat brain tumor was shown to react with a ganglioside present in fetal rat brain. We have found that this antigen is also present in human malignant melanoma tumors as well as many melanoma cell lines. The ganglioside from human melanoma cell lines migrates between GM1 and GM2 on one-dimensional thin layer chromatography. Analysis by two-dimensional thin layer chromatography with intermediate ammonia treatment suggests that the ganglioside contains one or more base-labile O-acyl esters. Mild base hydrolysis under conditions known to remove O-acyl esters results in complete loss of antigenic reactivity. Thus, the alkali-labile moiety is a critical component of the epitope recognized by the antibody. Analysis of the sialic acids of total gangliosides from [6-3H]glucosamine-labeled melanoma cells showed that approximately 10% of these molecules are O-acylated. Similar analysis of the purified ganglioside showed that greater than 30% of the sialic acids comigrated with authentic 9-O-acetyl-N-acetylneuraminic acid. The antibody did not cross-react with normal human skin melanocytes nor with any of a large number of normal human adult and fetal tissues. The antibody also did not react with numerous other malignant cell lines studied. These findings suggest that the antigenic epitope defined by antibody D1.1 contains an O-acylated sialic acid and may arise from aberrant O-acetylation occurring in human malignant melanoma cells.     

Association between allo-immunoreactive and xeno-immunoreactive subunits of a glycoprotein tumor-associated antigen

Summary Using allogeneic antibody, we previously described a tumor-associated antigen (TAA) in the urine of 68% of melanoma patients. The TAA was purified from urine of a melanoma patient and used as immunogen to develop a murine monoclonal antibody (AD1-40F4) and xenopolyclonal antibodies in a baboon. Sera from melanoma patients treated with whole melanoma cell vaccine were used as the source of human antibody to the glycoprotein antigen. Treatment with 2-mercaptoethanol and separation by sodium dodecyl sulfate/polyacrylamide gel electrophoresis resolved the high-molecular-mass glycoprotein TAA into smaller subunits. Immunoblot analysis indicates that the murine monoclonal antibody (AD1-40F4) recognized a 90–100-kDa subunit of the antigen while human anti-TAA antibodies primarily recognized a 65-kDa subunit in addition to the 90–100-kDa subunit. Baboon polyclonal antibodies recognized the same subunits plus a 120-kDa subunit. Blocking studies indicated that the murine monoclonal and baboon polyclonal antibodies recognized the closely related epitopes on the 90–100-kDa subunit, while human antibodies recognized an epitope entirely distinct from that recognized by the mouse antibody. These results demonstrate the epitope complexity associated with the high-molecular-mass glycoprotein TAA.     

23例鼻腔鼻旁窦恶性黑色素瘤临床病理分析

目的研究鼻腔鼻旁窦恶性黑色素瘤的临床及病理特征。方法采用免疫组化SP方法对23例鼻腔鼻旁窦恶性黑色素瘤的临床及病理进行分析。结果23例鼻腔鼻旁窦恶性黑色素瘤中,男性15例（65．2％）,女性8例（34．8％）;最大年龄80岁,最小年龄45岁,平均年龄57岁;位于鼻腔19例（82．6％）,鼻旁窦4例（17．4％）,临床表现全部为鼻肿物;病理组织学类型,小圆细胞型12例（52．2％）,上皮样细胞型8例（34．8％）,梭形细胞型2例（8．7％）,多形性细型胞1例（4．3％）;含有黑色素13例（56．5％）,无黑色素10例（43．5％）;免疫组化染色,Vimentin,23例全部呈阳性反应,阳性率为100％,S—100和HMB45呈阳性反应的部为21例;阳性率都为91．3％,MelanA 19例呈阳性反应,阳性率占82．6％。结论23例鼻腔鼻窦恶性黑色素瘤,临床主要表现为鼻肿物,发病部位大多数在鼻腔,联合应用S-100,HMB45和Melan A弥漫阳性在与其组织学相似的肿瘤鉴别中是诊断鼻腔鼻窦恶性黑色素瘤的重要标准。     

Method of Melanin Bleaching in MIB1-Ki67 Immunostaining of Pigmented Lesions: A Quantitative Evaluation in Malignant Melanomas

The effect of melanin bleaching on the immunoreactivity of the MIB1-Ki67 antigen in pigmented melanocytic lesions was investigated. Eight paired non-pigmented and heavily pigmented malignant melanomas (6 primary melanomas and 2 secondary melanomas) were selected. Avidin–biotin immunoperoxidase complex (ABC) and microwave antigen retrieval were used in immunostaining. Sections were incubated with 10% H2O2 for 24h before immunostaining with primary antibody MIB1, or after the completion of immunostaining. Non-bleached controls were obtained by conducting the identical staining but omitting the bleaching procedure. In all heavily pigmented lesions bleached by 10% H2O2 before or after immunostaining, the melanin was bleached effectively and MIB1-positively stained cells were clearly seen. Cell counting in the non-pigmented group found that there were no significant differences in the percentage of MIB1-positive melanoma cells (%MIB1) between non-bleached controls and those sections which had been bleached by 10% H2O2 either before or after the immunostaining. The results suggest that hydrogen peroxide can effectively bleach melanin in pigmented melanocytic lesions without significantly affecting MIB1-Ki67 immunolabelling.     

Fine Needle Aspiration Cytology and Immunocytochemistry of Metastatic Melanoma

The cytological and immunological findings of 81 metastatic melanomas are described. Fine needle aspiration was performed from secondary deposits in lymph nodes (38), subcutaneous and soft tissue (36), abdomen (5), lung (1) from 67 patients with histologically verified malignant melanoma. One patient had disease which had spread into the cerebrospinal fluid. Cytomorphologically the cases were classified as classical (47%), carcinoma-like (22%), spindle cell type (14%), lymphoma like (6%), undifferentiated (6%), myxoid type (3%), and clear cell type (2%). All cases were immunologically characterized using antibodies to S-100, vimentin and cytokeratin. All cases were S-100 positive and the majority (96%) reacted with antibodies to vimentin. A weak heterogenous reactivity to cytokeratin antibody was detected in only eight cases. The HMB45 antibody was applied to 20 cases and 16 (80%) of these tumours were positive. In summary, we found that an immunological characterization was necessary to conclusively diagnose over 50% of metastatic melanomas which presented with an equivocal cytological picture.     

Criteria for selecting monoclonal antibodies with respect to accumulation in melanoma tissue

Summary Immunohistology provides a necessary but insufficient criterion for selecting monoclonal antibodies (MAbs) capable of tumour targeting in vivo. Additional selection procedures have been evaluated using a panel of anti-melanoma MAbs, including immunoreactivity of (labelled) MAbs, antibody affinity, kinetics of binding and release, apparent antigen density and accumulation in nude mouse transplants. According to these criteria, MAbs M.2.7.6 and M.2.9.4 showed the most favourable properties, i.e. high immunoreactivity and pronounced internalization into melanoma cells. With MAbs M.2.10.15 and KG 6–56, moderate immunoreactivity and a binding pattern characterized by temperature dependence in the absence of internalization was observed. According to the paired label assay, all four MAbs showed specific accumulation into solid melanoma tissue. However, application in the patient still requires evaluation of the side effects of antigen cross-expression on normal human tissues.     

Experimental Boron Neutron Capture Therapy for Melanoma: Systemic Delivery of Boron to Melanotic and Amelanotic Melanoma

The boron-containing melanin precursor analogue p-boronophenylalanine (BPA) has previously been shown to selectively deliver boron to pigmented murine melanomas when administered in a single intragastric dose. If boron neutron capture therapy is to become a clinically useful method of radiation therapy for human malignant melanoma, the boron carrier must be capable of delivering useful amounts of boron to remote tumor sites (metastases) and to poorly pigmented melanomas. We have now determined the ability of BPA to accumulate in several nonpigmented melanoma models including human melanoma xenografts in nude mice. The absolute amount of boron in the nonpigmented melanomas was about 50% of that observed in the pigmented counterparts but was still selectively concentrated in the tumor relative to normal tissues in amounts sufficient for effective neutron capture therapy. Single intragastric doses of BPA resulted in selective localization of boron in the amelanotic Greene melanoma carried in the anterior chamber of the rabbit eye and in a pigmented murine melanoma growing in the lungs. The ratio of the boron concentration in these tumors to the boron concentration in the immediately adjacent normal tissue was in the range of 3:1 to 4:1. These distribution studies support the proposal that boron neutron capture therapy may be useful as a regional therapy for malignant melanoma.     

Immunolocalization of lactoferrin in surgically resected pigmented skin lesions

Lactoferrin (Lf) expression was determined immunohistochemically in 57 formalin-fixed paraffin-embedded bioptic samples obtained from an equal number of patients treated by surgery to remove pigmented skin lesions (nevi = 23; melanoma = 12; vulgaris and seborrhoeic warts = 12; basal cell carcinoma = 10); in addition, 10 specimens of normal skin were studied as control. On 3 mm thick sections, depigmentation and antigen retrieval procedures were performed. The Lf immunoreactivity was revealed by a rabbit anti-human Lf. Quantification of Lf immunoreactivity was performed using an intensity-distribution (ID) score. Melanocytic cells, regardless of their benign or malignant nature, were consistently stained, with no significant differences in the Lf ID-score between melanomas or nevi. A different intensity of Lf immunoreactivity was encountered in superficial portions of warts, exclusively inside squamous epithelial cells arranged in sheets or whorls of keratin. On the contrary, basal cell carcinomas were always unstained, while a slight Lf positivity was found in focal keratinized areas present in two tumours showing baso-squamous differentiation. The Lf immunoreactivity was localized in the cytoplasm and only occasionally in the nucleus. The biological meaning of Lf in these cases of human skin specimens remains unexplained, although it cannot be ruled out that Lf might be involved in the defense system against tumours, or alternatively, may be used by cells requiring iron availability for their turnover. Moreover, the immunohistochemical expression of Lf in melanocytic lesions might be also related to a Lf-melanin interaction. Finally, the involvement of Lf in skin squamous non-neoplastic elements could be related to its role as one of the molecules modulating an unspecific inflammatory or anti-oxidant response.     

Pitfalls in the diagnosis of malignant melanoma

The histological appearance of benign melanocytic naevi and malignant melanomas can be variable, causing in a significant number of cases severe differential diagnostic problems. The early, thin (less than 1 mm) melanomas have to be differentiated from naevi containing dominant junctional or lentiginous component or pagetoid melanocytosis and from some epithelial tumours, while in cases of thick lesion the diagnosis of thick melanoma, Spitz naevus, deep penetrating naevus or cellular blue naevus should be considered for example. The morphology of the so-called atypical Spitz naevus and atypical pigmented spindle cell naevus show overlapping with malignant melanoma and sometimes in these cases the biological behaviour cannot be assessed. The variable appearance of malignant melanoma is illustrated by the fact that different superficial soft tissue tumours with epithelioid and/or spindle cells or with pigment can mimic it. The rare balloon cell and signet ring cell melanoma is a mimicker of primary or metastatic carcinoma and the desmoplastic variant is often misdiagnosed as benign mesenchymal lesion. Lymph node metastasis of melanoma, when the primary tumour is not known, may raise the possibility of interdigitating reticulum cell tumour or anaplastic large cell lymphoma.     

Molecular profile, tissue distribution and prognostic evaluation of a human melanoma-carcinoma antigen recognized by the murine monoclonal antibody B1.1

Using the murine monoclonal antibody (MoAb) B1.1 we have analyzed the immunochemical profile and the tissue distribution of a human melanoma associated antigen (MAA) carrying an epitope shared by the 180 kd CEA. Results of this study have demonstrated that the epitope expressed by the MAA is carried by a distinct set of molecules of 110-140 kd. Similarly to the 180 kd CEA molecules synthesized by carcinomas, the expression of the melanoma associated CEA like components (MA-CEA) is upregulated by IFN-alpha. The tissue distribution of MA-CEA is not restricted to malignant primary and metastatic melanocytic lesions but is found also at low levels in 64% of benign nevi. No circulating CEA was found in patients bearing widespread metastatic disease of MA-CEA positive lesions. Preliminary clinical evaluation of stage I melanoma patients bearing MoAb B1.1 positive lesions has not shown a significative prognostic association of this phenotypic marker with clinical course of the disease.