An immunoperoxidase study of S-100 protein distribution in normal and neoplastic tissues

Serum Protein S-100 Predicts Clinical Outcome in Patients with Melanoma Treated with Adjuvant Interferon – Comparison with Tyrosinase RT-PCR

OBJECTIVE

To study the clinical value of the determination of serum S-100 protein as a single tumor marker or in combination with tyrosinase RT-PCR in patients with melanoma receiving adjuvant interferon.

PATIENTS AND METHODS

Patients were tested for serum S-100 protein luminoimmunometric assay and for blood tyrosinase mRNA (RT-PCR), before starting interferon and every 2-3 months thereafter.

RESULTS

One hundred and six patients (stage IIA, 27; IIB, 19; III, 49; and IV, 11) were included in the study. Median follow-up was 51 months (range 2-76). In the univariate analysis, under treatment S-100 > or =0.15 microg/l and a positive RT-PCR correlated with a lower disease-free survival and overall survival (OS). In the multivariate analysis, clinical stage, under therapy positive RT-PCR and S-100 levels > or =0.15 mug/ml, were independent prognostic factors for OS. The hazard ratio for OS was 3.9 (95% CI, 1.67-9.15; p = 0.004) and 2.2 (95% CI, 1.05-4.6; p = 0.016) for S-100 > or =0.15 microg/l and positive RT-PCR, respectively. When both techniques where combined, a positive RT-PCR indicated a poorer clinical outcome only in patients with S-100 <0.15 microg/l.

CONCLUSIONS

S-100 > or =0.15 microg/l and a positive RT-PCR during adjuvant interferon therapy indicate a high risk of death in resected melanoma patients. S-100 determination has a higher positive predictive value than RT-PCR, while tyrosinase RT-PCR adds prognostic information in patients with S-100 <0.15 microg/l.

Giant pedunculated lipofibroma of the elbow

Lipofibromas are rare hamartomatous lesions almost exclusively involving the medial nerve and have been reported to date only in the adult population. The case of a giant pedunculated lipofibroma involving the radial nerve in the elbow of a 1-year-old child is presented.

Primary synovial sarcoma of the parotid gland

Synovial sarcoma typically develops in the deep soft tissues of the extremities in adolescents and young adults. Uncommonly, these tumors may arise (9%) in the head and neck region (9%), especially at the cervical and parapharyngeal sites. Primary synovial sarcoma of the parotid gland is a rare occurrence that may not uncommonly cause differential diagnostic difficulties. In these cases, an origin from within the gland rather than a secondary involvement by tumor from a surrounding structure must be confirmed. We report a new case of biphasic synovial sarcoma arising in the parotid gland and review the previously documented cases.

Serummarker des malignen Melanoms

Tumor markers in the serum of cancer patients have an important role in clinical diagnosis and in prognosis, and also in the monitoring of the patients' disease and response to therapy over time. The serum markers currently available for melanoma have only limited clinical use. Those most widely used in clinical applications are S100-beta, melanoma inhibitory activity, and lactate dehydrogenase; there are close correlations between the serum concentrations of these and tumor load. Regular determination of S100-beta and MIA levels during follow-up can therefore be used for early detection of a tumor relapse in melanoma patients, increased serum concentrations of these marker proteins being indicative of tumor growth. Patients with distant metastases from melanoma who present with elevated serum levels of S100-beta, MIA, or LDH have poorer overall survival than do patients whose serum concentrations are within normal ranges. These three markers can also be used to monitor the course of disease and therapy outcome in patients with distant metastases. Since there are no marker proteins for melanoma that are not dependent on tumor load, it is not currently possible to forecast the survival of patients who are tumor free after surgery. Serum markers are also not suitable for screening or for the diagnosis of primary melanomas.

S-100 protein immunoreactivity in the upper eyelid of the sheep Ovis aries

The aim of this work was to analyse the distribution pattern of S-100-immunoreactive elements in the upper eyelid of the sheep. This pattern may be of importance regarding the diagnosis and prognosis of eyelid tumours that are linked to deregulation of S-100 gene expression. Thirty upper eyelids taken from 15 adult male Ovis aries were studied by means of the peroxidase-antiperoxidase method for light microscopy. S-100-immunopositive cells were found in the eyelid edge. S-100-immunopositive steams and thinner fibres were found throughout the eyelid. These nerve processes typically were denser around glands, hair follicles and blood vessels. S-100-immunopositive elements may play a role as neuromodulator and also in the development of the vegetative innervation of the epithelium and its derivatives.

[P63 protein in the diagnosis of breast tubular carcinoma]

AIMS

To study and compare the expression of p63 protein and smooth muscle actin in breast tubular carcinoma (TC) and its main differential diagnoses, radial scar (RS)/complex sclerosing lesion (CSL).

MATERIALS AND METHODS

Immunohistochemistry techniques were used to search for p63 protein and smooth muscle actin antibodies in 10 patients with TC and fifteen with RS/CSL.

RESULTS

Myoepythelial cells were diffusely positive for both actin and p63 protein with a cytoplasmic (actin) or nuclear (p63) pattern in all patients with RS/CSL. Inversely, all TC were negative for p63. Actin antibodies failed to label myoepithelial cells in TC, but both vessels and stromal myoblasts were actin-positive, creating difficult interpretation situations. By contrast, p63 was consistently negative in these structures.

CONCLUSION

For the differential diagnosis between TG and CR/LSC, smooth muscle actin and p63 protein demonstrate equivalent sensitivity for the detection of myoepithelial cells. However, the nuclear pattern of p63 labeling gives a "cleaner" stain. In addition, p63 enables distinction between myoepithelial cells and myofibroblasts/vascular smooth muscle cells, offering increased specificity.

Granular Cell Tumor of the Breast

Granular cell tumors (GCT) are uncommon, usually benign, neoplasms that are thought to derive from Schwann cells of the peripheral nerves. They can originate anywhere in the body but are most frequently found in the head and neck, particularly in the oral cavity. When they are located in the breast, as may occur in 5–8 per cent of cases, the clinical and pathologic appearance is similar to that of a malignant tumor. Immunohistochemical analysis, including reactivity for periodic acid–Schiff, CD68, and S100 and negative reactivity for cytokeratin, is required for definitive diagnosis. Awareness of this tumor's unique characteristics might aid in differentiating it from the more common malignant tumors of the breast.

Temporal bone chondroblastomas

OBJECTIVES

To review temporal bone chondroblastomas in regards to their presentation, radiographic findings, histopathology, and treatment.Study design Case report and literature review.

METHODS

A case report of a 38-year-old man is reviewed who presented with left-sided mixed hearing loss, otalgia, otorrhea, and a left external auditory canal mass. A computed tomography scan revealed a 6-cm mass involving the petrous and squamous portions of the left temporal bone.

CONCLUSIONS

Temporal bone chondroblastomas are extremely rare osseous tumors with only 35 cases previously reported in the literature. Presenting symptomatology and pathology may be confused with more common lesions seen in the temporal bone. Diagnostic radiology, including computed tomography and/or magnetic resonance imaging, as well as immunohistochemical staining with S-100 protein may assist in making the diagnosis. Treatment is complete surgical excision with preservation of vital neurovascular structures.

The 'Abtropfung phenomenon' revisited: Dermal nevus cells from congenital nevi cannot activate matrix metalloproteinase 2 (MMP-2)

Since Unna's Abtropfung hypothesis, the process of migration of nevus cells in the dermis remains unknown. To investigate its mechanisms, we studied the role of gelatinases in dermal nevus cells obtained from congenital pigmented nevi, which are major actors in the remodeling of basement membrane proteins. Our previous studies have shown that dermal nevus cells express pro-matrix metalloproteinase (MMP)-2 exclusively and cannot return to the dermis when seeded together with keratinocytes on top of the dermis in a skin reconstruction model. To examine why MMP-2 was not in its active form, we used Western blot to study the expression of members of the MMP-2 activation pathway (membrane type 1-MMP and tissue inhibitor of metalloproteinase-2), which proved to be normally expressed. To induce the dermal passage of nevus cells artificially, we also tried to activate gelatinases with phorbol-12-myristate-13-acetate and epidermal growth factor, using epidermis reconstructed with nevus cells. No migration in the dermis could be triggered. We conclude that the absence of active MMP-2 is due to a functional blockade of its activation pathway and may prevent dermal nevus cells from reaching the dermal compartment in skin reconstructs. Furthermore, our findings reinforce the concept that dermal nevus cells originating from congenital nevi are in a quiescent status.

Anti-allergic drug olopatadine suppresses murine contact hypersensitivity and downmodulates antigen-presenting ability of epidermal Langerhans cells

Olopatadine hydrochloride is an H1-receptor-blocker but has other anti-allergic pharmacological potencies. We investigated whether olopatadine inhibits murine contact hypersensitivity, focussing on its modulatory action on epidermal Langerhans cells serving as antigen-presenting cells. While BALB/c mice were sensitized and challenged epicutaneously with hapten, they were administered intraperitoneally with olopatadine. Olopatadine at 1 or 0.2 mg/kg of weight significantly suppressed the sensitivity when injected at least once before sensitization or challenge. In olopatadine-injected mice, the ability of Langerhans cells to present hapten to primed T cells was reduced with decreased expression of MHC class II and co-stimulatory molecules. Langerhans cells exposed in vitro to 10(-5) or 10(-6) M olopatadine had less antigen-presenting activity than control, whereas neither T cell proliferation nor keratinocyte production of IL-1alpha and IP-10 was affected at these doses. These findings suggest that olopatadine downmodulates contact hypersensitivity at least partly by interfering with the antigen-presenting ability of Langerhans cells.

Immunohistochemical demonstration of 14-3-3 sigma protein in normal human tissues and lung cancers, and the preponderance of its strong expression in epithelial cells of squamous cell lineage

In order to confirm 14-3-3 sigma (sigma) protein distribution in human tissues, immunohistochemistry was performed using various paraffin-embedded human tissues. In normal human tissues, the strongest immunoreactivity for 14-3-3sigma protein was observed in squamous epithelia at various sites, followed by basal cells of the trachea, bronchus and basal or myoepithelial cells of various glands. Moderate to weak 14-3-3sigma immunoreactivity was seen in the epithelial cells of the alimentary tract, gall bladder, urinary tract and endometrium. In the lung, 14-3-3sigma immunoreactivity was also observed in hyperplastic type II alveolar cells and metaplastic squamous cells. Immunohistochemical study using non-small-cell lung cancers revealed that 14-3-3sigma immunoreactivity was stronger in squamous cell carcinomas than in adenocarcinomas. The present study revealed that 14-3-3sigma expression was exclusively present in various epithelial cells and had a tendency to be stronger in cells destined for squamous epithelium or differentiating toward squamous cells in human normal and neoplastic cells.

Structure and function of human sweat glands studied with histochemistry and cytochemistry

The basic structure and the physiological function of human sweat glands were reviewed. Histochemical and cytochemical techniques greatly contributed the elucidation of the ionic mechanism of sweat secretion. X-ray microanalysis using freeze-dried cryosections clarified the level of Na, K, and Cl in each secretory cell of the human sweat gland. Enzyme cytochemistry, immunohistochemistry and autoradiography elucidated the localization of Na,K-ATPase. These data supported the idea that human eccrine sweat is produced by the model of N-K-2Cl cotransport. Cationic colloidal gold localizes anionic sites on histological sections. Human eccrine and apocrine sweat glands showed completely different localization and enzyme sensitivity of anionic sites studied with cationic gold. Human sweat glands have many immunohistochemical markers. Some of them are specific to apocrine sweat glands, although many of them stain both eccrine and apocrine sweat glands. Histochemical techniques, especially immunohistochemistry using a confocal laser scanning microscope and in situ hybridization, will further clarify the relationship of the structure and function in human sweat glands.

Immunohistochemical demonstration of EMA/Glut1-positive perineurial cells and CD34-positive fibroblastic cells in peripheral nerve sheath tumors

To clarify the cellular composition of various peripheral nerve tumorous lesions (traumatic neuroma, 5 cases; schwannoma, 10 cases; neurofibroma, 14 cases; perineurioma, 3 cases; conventional malignant peripheral nerve sheath tumor (MPNST), 7 cases; perineurial MPNST, 4 cases), expression of several markers specific to nerve sheath cells, including glucose transporter protein 1 (Glut1) and CD34, were immunohistochemically investigated with highly sensitive detection methods. In normal nerves and neuromas, perineuriums were positive for Glut1 as well as for epithelial membrane antigen (EMA), and there were some CD34-positive fibroblast-like cells in the endoneurium. Schwannomas consisted principally of S-100 protein-positive Schwann cells, whereas a few CD34-positive fibroblastic cells were present in Antoni B areas. Neurofibromas and conventional MPNST exhibited a mixed proliferation of S-100 protein-, EMA/Glut1-, and CD34-positive cells, indicating a heterogeneous composition of the constituents. The catalyzed signal amplification (CSA) system demonstrated more numerous EMA-positive perineurial cells in neurofibromas than did the ENVISION+ method. Perineurial cell tumors (benign and malignant) were composed of EMA/Glut1-positive and S-100 protein-negative tumor cells. The present study confirmed the characteristic cellular composition to each nerve sheath tumor immunohistochemically and showed the usefulness of the nerve sheath cell markers. Glut1 as well as EMA are specific to perineurial cells, and CD34 seems to be immunoreactive to endoneurial fibroblasts.

Immunocytochemistry of myoepithelial cells in the salivary glands

MECs are distributed on the basal aspect of the intercalated duct and acinus of human and rat salivary glands. However, they do not occur in the acinus of rat parotid glands, and sometimes occur in the striated duct of human salivary glands. MECs, as the name implies, have structural features of both epithelial and smooth muscle cells. They contract by autonomic nervous stimulation, and are thought to assist the secretion by compressing and/or reinforcing the underlying parenchyma. MECs can be best observed by immunocytochemistry. There are three types of immunocytochemical markers of MECs in salivary glands. The first type includes smooth muscle protein markers such as alpha-SMA, SMMHC, h-caldesmon and basic calponin, and these are expressed by MECs and the mesenchymal vasculature. The second type is expressed by MECs and the duct cells and includes keratins 14, 5 and 17, alpha 1 beta 1 integrin, and metallothionein. Vimentin is the third type and, in addition to MECs, is expressed by the mesenchymal cells and some duct cells. The same three types of markers are used for studying the developing gland. Development of MECs starts after the establishment of an extensively branched system of cellular cords each of which terminates as a spherical cell mass, a terminal bud. The pluripotent stem cell generates the acinar progenitor in the terminal bud and the ductal progenitor in the cellular cord. The acinar progenitor differentiates into MECs, acinar cells and intercalated duct cells, whereas the ductal progenitor differentiates into the striated and excretory duct cells. Both in the terminal bud and in the cellular cord, the immediate precursors of all types of the epithelial cells appear to express vimentin. The first identifiable MECs are seen at the periphery of the terminal bud or the immature acinus (the direct progeny of the terminal bud) as somewhat flattened cells with a single cilium projecting toward them. They express vimentin and later alpha-SMA and basic calponin. At the next developmental stage, MECs acquire cytoplasmic microfilaments and plasmalemmal caveolae but not as much as in the mature cell. They express SMMHC and, inconsistently, K14. This protein is consistently expressed in the mature cell. K14 is expressed by duct cells, and vimentin is expressed by both mesenchymal and epithelial cells. After development, the acinar progenitor and the ductal progenitor appear to reside in the acinus/intercalated duct and the larger ducts, respectively, and to contribute to the tissue homeostasis. Under unusual conditions such as massive parenchymal destruction, the acinar progenitor contributes to the maintenance of the larger ducts that result in the occurrence of striated ducts with MECs. The acinar progenitor is the origin of salivary gland tumors containing MECs. MECs in salivary gland tumors are best identified by immunocytochemistry for alpha-SMA. There are significant numbers of cells related to luminal tumor cells in the non-luminal tumor cells that have been believed to be neoplastic MECs.

A corneal diffuse neurofibroma as a manifestation of von recklinghausen disease

PURPOSE

To report a case of a primary corneal diffuse neurofibroma in a patient with von Recklinghausen disease (NF-1).

METHODS

Case report. A physical examination and histopathology were performed. The immunohistochemical studies were performed using an avidin-biotin-peroxidase complex technique on formalin-fixed and paraffin-embedded tissue. Histologic sections from corneal tissue were incubated with primary antibodies against vimentin and S-100 protein. A complementary ultrastructural study of the same formalin-fixed and paraffin-embedded tissue was made.

RESULTS

The ophthalmologic examination revealed a yellowish-white elevated mass that involved the supratemporal cornea but not the limbus. Histologic study showed a tumor of the peripheral nerve sheath, a diffuse neurofibroma in the corneal stroma, and proliferation of spindle cells with markedly elongated nuclei. Cells comprising the tumor reacted with vimentin and S-100 protein, and the ultrastructural studies revealed myelinated nerve fibers confirming the diagnosis.

CONCLUSION

The development of a primary diffuse neurofibroma in the cornea of patients with von Recklinghausen disease is possible. The present case supports the statement that neurofibromas arising from the peripheral nerve sheath may involve any part of the body.

Comparison of five antibodies as markers in the diagnosis of melanoma in cytologic preparations

We determined the sensitivity and specificity of 3 novel antibodies (microphthalmia transcription factor [Mitf], Melan-A, and tyrosinase) as markers for melanoma in cytologic preparations and compared the results with those of commonly used markers (S-100 protein [S-100] and HMB-45). We stained 72 cell blocks from 40 patients with melanoma and 32 with nonmelanocytic malignant neoplasms with antibodies against S-100, HMB-45, Mitf, Melan-A, and tyrosinase. Histologic correlation was available in more than 95% of cases. Nuclear stainingfor Mitf and cytoplasmic stainingfor S-100, HMB-45, Melan-A, and tyrosinase in more than 10% of tumor cells was considered positive. All 3 novel markers demonstrated sensitivity superior to S-100 and HMB-45. HMB-45, Melan-A, and Mitf demonstrated specificities of 97%. S-100 protein and tyrosinase were less specific. Sensitivity and specificity for the combination Mitf+/Melan-A+ were 95% and 100%, respectively, whereas they were 80% and 100%, respectively, for S-100+/HMB-45+. Mitf Melan-A, and tyrosinase are sensitive markersfor epithelioid melanoma. Mitf and Melan-A seem more specific than S-100 and tyrosinase. An antibody panel consisting of Mitf and Melan-A is superior to a panel of S-100 and HMB-45 in the diagnosis of melanoma in cytologic specimens.

A comparative review of melanocytic neoplasms

Melanoma is a devastating disease frequently encountered within both veterinary and human medicine. Molecular changes linked with neoplastic transformation of melanocytes include mutations in genes that encode proteins intrinsic to the regulatory pathways of two tumor suppressor proteins (retinoblastoma protein and p53), proto-oncogene mutation to oncogenes, altered expression of epithelial cadherin and CD44 adhesion molecules, and upregulation of angiogenic factors and other growth factors. Histologic evaluation of the primary mass is the most common means of diagnosis, with cytology used more frequently to document metastasis. Melanoma's highly variable histologic and cytologic patterns can make diagnosis by either method problematic. Adherent epithelioid morphology, including signet ring forms, and nonadherent round and spindle forms are recognized, with pigmentation an inconsistent finding. The site of the tumor, the thickness of the primary tumor or depth of invasion, and the number of mitotic figures per high-power field or per millimeter are used histologically to predict biologic behavior, whereas site and degree of pleomorphism are typically used for cytologic preparations. Diagnosis of amelanotic melanoma can be aided by ancillary diagnostic techniques. Tumor cells are usually positive for vimentin, S100, neuron-specific enolase, and Melan-A, and negative for cytokeratin. Melan-A as a positive marker is not as sensitive as the others are but is likely more specific. Monoclonal antibodies to human melanosome-specific antigens 1 and 5 cross-react with canine antigens for a combined sensitivity rate of 83%. Mouse monoclonal antibody IBF9 specifically recognizes canine melanoma antigen and also has good sensitivity. Serologic markers, including cytokines, cell adhesion molecules, and melanoma-inhibitory activity, are being investigated as potential sentinels of melanoma. Currently, there is no single diagnostic technique capable of differentiating benign from malignant melanocytic neoplasms or predicting survival time.

Soluble HLA-DR is a potent predictive indicator of disease progression in serum from early-stage melanoma patients

Despite numerous therapeutic options, the prognosis of malignant melanoma, once metastasized, is still poor. Thus, the search for reliable methods to identify patients with high risk of disease progression as early as possible is of major importance. In our study, we analyzed the predictive value of soluble HLA-DR (sHLA-DR) in comparison to S100-beta in serum from 183 melanoma patients of different stages of disease and with or without current therapy using immunosorbent assays. sHLA-DR serum levels of 121 healthy individuals served as controls. We found significantly (p < 0.0005) reduced sHLA-DR serum levels in melanoma patients (0.70 +/- 0.08 SEM microg/ml) compared to controls (1.49 +/- 0.10 SEM microg/ml). Reduced sHLA-DR and increased S100-beta levels were associated with advanced disease stages and tumor load. S100-beta was increased under cytostatic therapy (p < 0.0005), whereas sHLA-DR was not influenced by therapy modalities. Univariate analysis showed an association of sHLA-DR < 0.3 microg/ml and S100-beta > 0.12 microg/l with poor overall (p = 0.021 and p = 0.0009) and progression-free survival (p < 0.0005 and p = 0.0025). Multivariate analysis revealed disease stage (p = 0.0093) and tumor burden (p < 0.0005) as independent predictive factors for overall survival, and sHLA-DR (p = 0.0007) and tumor burden (p = 0.0015) for progression-free survival. In contrast to S100-beta, sHLA-DR serum concentrations < 0.3 microg/ml were strongly associated (p = 0.0001) with poor progression-free survival in a subgroup of 60 nonmetastasized patients. In conclusion, our results suggest sHLA-DR as a potent prognostic serum marker in melanoma patients superior to S100-beta in helping to identify early-stage patients at high risk of disease progression.

Immunohistochemical detection of melanoma-specific antigens in spontaneous canine melanoma

Twenty-five formalin-fixed, paraffin wax-embedded canine melanomas were examined immunohistochemically by an immunoperoxidase method to assess their reactivity with three human melanoma-specific monoclonal antibodies (HMB-45, MEL-1, NK1/C3). HMB-45 and MEL-1 reacted with 22/25 (88%) and 18/25 (72%) of canine melanomas, respectively, but only after microwave antigen retrieval and pretreatment with potassium permanganate and oxalic acid (KMnO(4)/OA). Positive reactivity to HMB-45 and MEL-1 was as follows: oral melanomas, 13/16 and 9/16, respectively; cutaneous melanomas, 8/8 and 8/8; melanoma of the digit, 1/1 and 1/1; all pigmented melanomas, 16/18 and 14/18; all amelanotic tumours, 6/7 and 4/7. HMB-45 immunolabelling was characterized by a diffuse granular cytoplasmic pattern within the tumour cells, and MEL-1 labelling by a cytoplasmic pattern with sporadic nuclear localization. In most tumours the labelling was homogeneous, but some showed a multifocal distribution. Generally, a higher percentage of canine melanomas was labelled by HMB-45 than by MEL-1. NK1/C3 failed to label any of seven melanomas tested, regardless of KMnO(4)/OA-pretreatment. Of 16 non-melanocytic tumours (specificity controls), 15 showed no significant reactivity with HMB-45, the exception being one of three plasmacytomas. Immunolabelling by MEL-1 on non-melanocytic tumours was not pursued, due to the poor sensitivity of this antibody as compared with that of HMB-45.

Redefining the skin's pigmentary system with a novel tyrosinase assay

In mammalian skin, melanin is produced by melanocytes and transferred to epithelial cells, with the epithelial cells thought to receive pigment only and not generate it. Melanin formation requires the enzyme tyrosinase, which catalyzes multiple reactions in the melanin biosynthetic pathway. Here, we reassess cutaneous melanogenesis using tyramide-based tyrosinase assay (TTA), a simple test for tyrosinase activity in situ. In the TTA procedure, tyrosinase reacts with biotinyl tyramide, causing the substrate to deposit near the enzyme. These biotinylated deposits are then visualized with streptavidin conjugated to a fluorescent dye. In the skin and eye, TTA was highly specific for tyrosinase and served as a sensitive indicator of pigment cell distribution and status. In clinical skin samples, the assay detected pigment cell defects, such as melanocytic nevi and vitiligo, providing confirmation of medical diagnoses. In murine skin, TTA identified a new tyrosinase-positive cell type--the medullary cells of the hair--providing the first example of cutaneous epithelial cells with a melanogenic activity. Presumably, the epithelial tyrosinase originates in melanocytes and is acquired by medullary cells during pigment transfer. As tyrosinase by itself can generate pigment from tyrosine, it is likely that medullary cells produce melanin de novo. Thus, we propose that melanocytes convert medullary cells into pigment cells by transfer of the melanogenic apparatus, an unusual mechanism of differentiation that expands the skin's pigmentary system.

Dermal melanoma with schwannoma-like differentiation in a brown bullhead catfish (Ictalurus nebulosus)

A dermal melanoma with histologic similarities to mammalian melanocytic schwannomas was diagnosed in a wild-caught brown bullhead catfish (Ictalurus nebulosus). The diagnosis was based on cytologic, histopathologic, immunohistochemical, and ultrastructural findings. The neoplasm protruded from the cutaneous surface of the dorsal midline immediately caudal to the dorsal fin, was diffusely black and focally ulcerated, and was attached to the underlying skin by a broad-based stalk. Cytologically, the tumor was composed of a monomorphic population of melanophores, the melanin-producing and storing cells within the dermis and epidermis of fish that are partially responsible for rapid color changes. Histopathologic examination of the neoplasm revealed an unencapsulated, well-circumscribed, moderately cellular neoplasm composed of 2 distinct cell populations: spindle cells arranged in a "herringbone" pattern and numerous melanophores. The spindle cells had scant bipolar eosinophilic cytoplasm, with small centrally located vesicular nuclei; nucleoli were not seen. The histologic appearance was similar to that described for mammalian melanocytic schwannomas. Immunohistochemically, the spindle cells exhibited positive cytoplasmic staining for S-100 protein but were negative for vimentin, neurofilament protein, and glial fibrillary acidic protein. Ultrastructurally, the tumor consisted of neoplastic spindle cells with rudimentary cell junctions, actin bundles, and few melanosomes and melanophores with abundant intracytoplasmic melanosomes.

Use of immunocytochemical techniques in canine melanoma

The staining patterns of the monoclonal antibodies S-100 and Melan-A in canine melanoma were assessed based on cytological specimens of six canine melanomas (four benign, two malignant). In addition, eight regional lymph nodes of the two dogs with malignant melanomas were stained using these markers. For reference, all specimens were also evaluated immunohistochemically using S-100 and Melan-A. To assess the immunocytochemical specificity of both antibodies, various canine tumours and normal tissues were stained. The immunocytochemical staining results of the canine melanomas and the regional lymph nodes showed high conformity with the immunohistochemical reactivity patterns for S-100 and Melan-A. The specificity of Melan-A was higher compared with S-100. Melan-A, in particular, may be helpful for the cytological diagnosis of canine melanoma.

Pigmented epidermal cysts

There are few reports documenting the presence of melanin or melanocytes in epidermal cysts. One hundred and twenty five epidermal cysts from Indian patients were analyzed for the presence of melanin pigment and their sites were noted. A Masson's Fontana stain and immunohistochemistry for S-100 protein and HMB 45 was performed for localization of melanin and melanocytes within the epidermal cysts. Seventy-nine (63%) of the epidermal cysts showed presence of melanin pigment or melanocytes to a variable extent. Melanin was not present in epidermal cysts occurring along lines of fusion of skin folds during embryonogenesis (e.g., ventral midline, inner canthus, nose, upper lip and in the distal most parts like leg and foot and also scrotum). Ten of the 79 epidermal cysts showed extensive accumulation of melanin pigment and infiltration with melanophages in the cyst wall. Four of these patients gave history of trauma and the follow-up was uneventful in two of them. Pigmentation of epidermal cysts thus follows a definite anatomic pattern and is dependent on the natural skin color. Large amount of pigment accumulation within epidermal cysts occurs after cyst rupture and is not associated with hemochromatosis as was believed in the past.

Microphthalmia transcription factor: a sensitive and specific marker for malignant melanoma in cytologic specimens

BACKGROUND

The diagnosis of melanoma can be difficult because of shared cytomorphology with other malignant neoplasms. The most commonly used melanocytic markers, anti-S-100 protein and HMB-45 antigen, have limited specificity and sensitivity, respectively. Microphthalmia transcription factor (Mitf) is a nuclear transcription factor critical for the development and survival of melanocytes and has been shown as a sensitive and specific marker for melanoma in histologic specimens.

METHODS

To evaluate the efficacy of Mitf as a marker for melanoma in cytologic preparations, 81 cell blocks from 44 patients with melanoma and 37 patients with nonmelanoma malignancies (29 patients with carcinoma, 4 patients with mesotheliomas, 2 patients with lymphoma, and 2 patients with islet cell tumors) were stained with monoclonal antibodies against Mitf (clone D5), S-100 protein, and HMB-45 antigen. The staining was evaluated blindly by three independent observers. The presence of nuclear staining for Mitf and cytoplasmic staining for S-100 protein or HMB-45 antigen in > 10% of tumor cells was considered positive staining for each antigen.

RESULTS

Forty-four melanomas (100%), including all 3 spindle-cell melanomas, were positive for Mitf. All nonmelanoma neoplasms were negative with only one exception: One mammary carcinoma showed rare (< 10%), weak nuclear staining with Mitf. The sensitivity and specificity of Mitf as a marker for melanoma were both 100%, whereas the sensitivity of HMB-45 antigen was 90.4%, and the specificity of S-100 protein was 70.3%.

CONCLUSIONS

Mitf is a sensitive and specific marker for malignant melanoma, including the spindle-cell variant, in cytologic specimens and may be superior to the current standard melanocytic markers, S-100 protein and HMB-45 antigen.

Diverse differentiation in malignant peripheral nerve sheath tumours associated with neurofibromatosis-1: an immunohistochemical and ultrastructural study

AIMS

The diverse histological features in malignant peripheral nerve sheath tumours (MPNSTs) associated with NF-1 were investigated by immunohistochemical and electron microscopic analysis. Our study is focused on the differentiation of the tumour cells in the heterogeneous components.

METHODS AND RESULTS

Twenty-three cases were classified as conventional type, epithelioid type, anaplastic type, and heterogeneous type, and divided into three groups by the presence of S100 protein (S100)-positive cells in each tumour; Group A was defined as having >50% S100+ cells, Group B as having <50%, and Group C as cases with no positive cells. To investigate the differentiation of the tumour cells, the morphology and immunoreactivity for neural or mesenchymal markers among the three groups were compared. For the identification of Schwannian, perineurial, and endoneurial differentiation, markers for S100, EMA and CD34 were used, respectively. In three tumours of the Group A type, there were no cases showing differentiation towards perineurial or endoneurial cells, or formation of heterogeneous components. In nine tumours of the Group B type, one tumour expressed EMA and CD34, suggesting probable perineurial and/or endoneurial differentiation. One tumour showed rhabdomyoblastic differentiation. Three tumours showed cartilaginous or osteogenic differentiation, and one of the three also showed a focal vascular differentiation. The surrounding areas of the heterogeneous components were composed of mixed S100+ cells and S100- cells. S100- cells in the areas were positive for CD34 in one case. In 11 tumours of Group C type, one tumour expressed EMA and CD34 suggesting perineurial and/or endoneurial cell differentiation. Three tumours showed rhabdomyoblastic differentiation. The tumour cells around the heterogeneous components in the three cases were negative for EMA and CD34.

CONCLUSION

Our results suggest that tumour cells differentiating to Schwann cells are not the only component of MPNSTs. Furthermore, tumour cells other than Schwann cells are largely related to the formation of the heterogeneous components in MPNSTs associated with NF-1.

S100A6 preferentially labels type C nevus cells and nevic corpuscles: additional support for Schwannian differentiation of intradermal nevi

BACKGROUND

Melanocytic nevi typically show a morphologic sequence of maturation from epithelioid "type A" cells to fusiform, Schwann cell-like "type C" cells with dermal descent. Nevi may also produce Wagner-Meissner-like structures (nevic corpuscles). Previous studies have shown that this maturation of intradermal nevi recapitulates intermediate stages in Schwann cell development. In intradermal nevi, we have evaluated the pattern of S100A6 protein, a form of S100 found in Schwann cells.

METHODS

Formalin-fixed, paraffin-embedded archival tissues were evaluated by immunohistochemistry using antibodies specific for S100A6 and S100B in 38 intradermal nevi (IDN). Ten neurofibromas (NF), 3 Schwannomas (SCH), 2 palisaded and encapsulated neuromas (PEN), and 2 granular cell tumors (GCT) were included as positive controls since these lesions have large numbers of Schwann cells.

RESULTS

Melanocytic nevi demonstrated preferential anti-S100A6 staining of "type C" cells (36/38; 28 strong, 8 weak) and nevic corpuscles (25/38; 19 strong, 6 weak) compared to "type A" cells (17/38; 17 weak) and "type B" cells (17/38; 4 strong, 13 weak). All NF, SCH, and PEN stained strongly with anti-S100A6. Both GCT were negative with anti-S100A6 but positive with anti-S100B.

CONCLUSIONS

The pattern of S100A6 expression in intradermal nevi further supports the hypothesis that maturation in these lesions recapitulates features of Schwann cell differentiation. The lack of S100A6 expression by both GCT suggests that these lesions have lost this feature of Schwann cells, which may play a role in their peculiar phenotypic appearance.

p63, a p53 homologue, is a selective nuclear marker of myoepithelial cells of the human breast

Myoepithelial cells (MCs) constitute the basal cell layer of normal mammary epithelia, and their identification is of particular diagnostic value because they are retained in most benign lesions while being lost in malignancy. Several MC immunocytochemical markers are currently available for diagnostic purposes, with special reference to smooth muscle-related antigens. p63 is a member of the p53 gene family, and its germline mutations are associated with severe mammary developmental defects in both rodents and humans. Different p63 isoforms have been identified, some of which (DeltaNp63) are preferentially expressed in the epithelial basal cells of different organs and have been considered as possible markers of stem cells/reserve cells. We investigated immunohistochemically 384 samples of normal and diseased human breast, including 300 invasive carcinomas, using four antibodies recognizing all p63 isoforms, or the DeltaNp63 isoforms. Twenty cytologic specimens were also investigated. Furthermore, snap-frozen tissue samples from three fibroadenomas and 10 invasive ductal carcinomas with their paired non-neoplastic tissues and three corresponding lymph node metastases were evaluated for the expression of p63 mRNA by RT-PCR. In normal breast tissue p63 immunoreactivity was confined to the nuclei of MCs. In all benign lesions p63-immunoreactive cells formed a continuous basal rim along the epithelial structures. Stromal cells, and in particular myofibroblasts, were consistently unreactive. Adenomyoepitheliomas showed nuclear staining in most neoplastic cells. A peripheral rim of p63-immunoreactive cells was retained surrounding lobular and ductal carcinoma in situ, although it was discontinuous as opposed to the normal structures. Invasive breast carcinomas were consistently devoid of nuclear p63 staining, with the exception of the two adenoid-cystic carcinomas, of the two ductal carcinomas with squamous metaplasia, and of 11 (4.6%) ductal carcinomas not otherwise specified, showing p63 immunoreactivity in a minor fraction (5-15%) of the neoplastic cells. In comparison with other MC markers, p63 was the most specific, being restricted exclusively to MCs, whereas antibodies to smooth muscle actin and, to a lesser extent, calponin also decorated stromal myofibroblasts. In the cytologic preparations p63 immunoreactivity was a consistent feature of "naked nuclei" and of a subset of cells surrounding benign epithelial clusters. RT-PCR experiments with primers specific for different p63 isoforms documented that normal tissues and fibroadenomas preferentially expressed the DeltaNp63 isoforms. Our study demonstrates that in normal and pathologic breast tissues MCs consistently express the DeltaNp63 isoforms. We suggest p63 as a reliable, highly specific, and sensitive MC marker in both histologic and cytologic preparations. Furthermore, because p63 immunoreactivity in adult epithelia is normally restricted to progenitor cells, it can be speculated that it might be a clue for the identification of the still elusive breast progenitor cells.

Spindle cell carcinoids of the lung with paraganglioid features: a reappraisal of their histogenetic origin from paraganglia using immunohistochemical and electronmicroscopic techniques

Five cases of spindle cell carcinoids of the lung were analyzed by immunohistochemical and ultrastructural technique. They were found to be biphasic tumors composed of the major component of neuroendocrine cells (chief cells) and a minor component of dendritic cells (supporting cells). The chief cells displayed positivity for neuroendocrine phenotypic antigenic markers: neuron specific enolase (NSE), chromogranin A, and synaptophysin. They contained varying numbers of dense-core granules by electron microscopy. In addition, the chief cells expressed cytoplasmic positivity for cytokeratins. The supporting cells were dendritic in appearance and displayed strong positivity for S-100 protein in all cases. Glial fibrillary acidic protein was positive in two cases. On electron microscopy, the supporting cells were agranular and found along the external lamina surrounding the nests of tumor cells. In two cases, rare ganglion cell-like cells were present. The histomorphologic, immunohistochemical, and ultrastructural features were contrastingly different from the classical pulmonary carcinoid and rather resembled gangliocytic paragangliomas arising from small intestine and spine. It is proposed that pulmonary carcinoids with biphasic features are better designated as gangliocytic paragangliomas of the lung rather than paraganglioid carcinoids.

Spindle cell epithelioma of the vagina shows immunohistochemical staining supporting its origin from a primitive/progenitor cell population

Spindle cell epitheliomas of the vagina (SCEVs) coexpresses epithelial and mesenchymal markers and were first described as a "mixed tumors of the vagina." However, unlike mixed tumors of other organs, which are believed to originate from myoepithelial cells, SCEVs neither immunohistochemically nor ultrastructurally show features of myoepithelial cells. The present expanded battery of immunohistochemical stains is presented on this rare tumor, including cytokeratin AE1/AE3, CK7, CK20, S100 protein, epithelial membrane antigen, alpha-smooth muscle actin, desmin, CD34, CD99, Bcl-2, vimentin, estrogen and progesterone receptors, and Ki-67. There was minimal expression of alpha-smooth muscle actin and negative staining with S100 protein, with coexpression of cytokeratins and vimentin and expression of estrogen and progesterone receptors, as previously reported in SCEVs. In addition, diffuse expression of CD34, CD99, and Bcl-2 immunohistochemical stains was found, which has not previously been reported. The coexpression of CD34, CD99, and Bcl-2 in SCEVs is consistent with its origin from a primitive/progenitor cell population.

Immunohistochemical and ultrastructural evidence that dendritic cells infiltrate stenotic aortocoronary saphenous vein bypass grafts

We earlier speculated that antigen-presenting dendritic cells may be involved in the immune reactions leading to saphenous vein bypass graft failure. The purpose of this study was to confirm whether dendritic cells are present in stenotic human saphenous vein bypass grafts. Segments of stenotic saphenous vein grafts were explanted from 14 patients at re-do bypass operation and ten normal saphenous veins were harvested during femoro-popliteal grafting. Sections of specimens were analysed using cell type specific antibodies to identify dendritic cells (CD1a, S-100), T-lymphocytes (CD3), macrophages (CD68), smooth muscle cells (alpha-SMA) and endothelial cells (FVIII). Dual immunostaining, confocal immunofluorescent laser scanning microscopy and electron microscopy were used. Stenotic grafts showed structural alterations of intimal hyperplasia and varying degrees of atherosclerotic degeneration. No cells expressing CD1a and S-100 were observed in the intima and media of normal saphenous veins. Cells expressing these antigens were present around areas of medial neovascularization and within intimal atherosclerotic lesions in saphenous vein bypass grafts. Electron microscopy demonstrated the presence of cells containing a well-developed tubulovesicular system which is unique to cells from the dendritic cell family. Double immunohistochemistry and confocal immunofluorescent microscopy revealed the co-localization of T-lymphocytes with dendritic cells. Dendritic cells are present in stenotic saphenous vein bypass grafts. Dendritic cells may be responsible for antigen presentation and modulation of immune reactions in accelerated graft atherosclerosis through their interaction with T-lymphocytes.

Microcystic adnexal carcinoma: an immunohistochemical study including markers of proliferation and apoptosis

Microcystic adnexal carcinoma (MAC) is the prototype for a subset of locally aggressive adnexal carcinomas (LAACs). Ultraviolet radiation (UVR) and UVB signature p53 mutations are implicated in the etiology of the most common cutaneous carcinomas. However in MACs, the role of UVR and p53 mutations is unknown. In addition, controversy still exists regarding the patterns of differentiation within these tumors. The objective of this study was to determine the expression patterns of immunohistochemical markers for p53, Ki-67, c-erbB-2, and Bcl-2 in MACs, and to compare these patterns with two MAC histologic stimulants: sclerosing type basal cell carcinomas (sBCCs) and desmoplastic trichoepitheliomas (dTEs). Other objectives were to compare expression patterns of cytokeratin (CK) AE1/AE3, CK7, CD20, endothelial membrane antigen (EMA), Ber-EP4, CD34, alpha-smooth muscle actin (SMA), and S-100 protein in MACs with its histologic simulators, and to determine the usefulness of all the immunohistochemical studies in diagnosis. Immunohistochemical markers were performed on 10 MACs, 10 sBCCs, and four dTEs. They included p53, Ki-67, c-erbB-2, Bcl-2, CK AE1/AE3, CK7, CD20, EMA, Ber-EP4, CD34, S-100 protein, and alpha-SMA. MACs expressed p53 in less than 25% of the tumor cells in only two cases (20%), and both cases showed only moderately intense staining, whereas 80% of the sBCCs were positive and showed intense staining, and all dTEs were negative. In MACs, less than 5% of the tumor cells were Ki-67 positive, whereas the sBCCs showed 20% to 40% Ki-67-positive tumor cells and dTEs showed rare Ki-67-positive cells. Bcl-2 was expressed focally in MACs, diffusely in sBCCs, and in scattered cells in dTEs. All tumors were negative for c-erbB-2. CD34, CK7, EMA, Ber-EP4, S-100 protein, and alpha-SMA all showed a distinctive pattern of staining in MACs. Although MACs arise commonly in chronically sun-exposed skin, increased expression of p53 is not found frequently. Overexpression of c-erbB-2 does not appear to be a factor in the development and progression of these adnexal tumors. Bcl-2 is expressed in MACs, but not diffusely as in sBCCs. The low level of Ki-67 supports a low proliferative rate, and other immunohistochemical markers support divergent patterns of adnexal differentiation in MACs. Immunohistochemical studies may help to differentiate MAC from sBCCs and dTEs.

Granular cell tumor of the male breast: report of a case

We treated a 35-year-old male with a granular cell tumor in the right breast. Physical examination revealed a solid, flattened, round 3.2 x 2.5-cm mass with an irregular surface, covering skin fixation and right axillary lymphadenopathy. Mammography revealed a well-demarcated high-density mass with a minimal starburst appearance. Ultrasonography revealed a hypoechoic, nonhomogeneous mass with an acoustic shadow. Several enlarged lymph nodes in the right axilla were removed at the time of breast tumor excision. Histologically, the tumor featured nests of round or polygonal cells with abundant eosinophilic cytoplasmic granules and small round nuclei, and the enlarged lymph nodes in the right axilla exhibited no metastasis. Immunohistochemically, there was positive staining for S-100 protein, neuron-specific enolase, and vimentin. The tumor also stained for macrophage CD-68, alpha1-antichymotrypsin, and myoglobin. These immunohistochemical findings suggested the tumor cells to be undifferentiated mesenchymal cells which demonstrated the properties of neurogenic cells and histiocytes.

Adenoid cystic carcinoma of the breast: report of a case

Adenoid cystic carcinoma of the breast is an uncommon form of cancer, and only a few articles have described the cytological findings of this disease. We report herein the case of a 48-year-old woman who presented with a breast mass beneath the nipple, the aspirate from which consisted of globules of mucous balls surrounded by epithelial cells with scant cytoplasm and hyperchromatic nuclei. Microscopically, the tumor was formed by myoepithelial cells and glandular epithelial cells in a biphasic pattern. Immunohistochemical study revealed positivity for smooth muscle actin. A left total mastectomy with axillary lymph node dissection was performed. None of the 22 axillary lymph nodes contained metastases, and the patient remains well and free from recurrence 29 months after her operation. This case report provides some information about the cytological diagnosis and the accuracy of fine-needle aspiration, which must be considered despite the rarity of this disease.

Monitoring malignant melanoma with the S-100B tumour marker

To assess the usefulness of the S-100B tumour marker in monitoring therapy and during follow-up we measured S-100B serum concentration in 31 patients participating in a phase I trial studying the effect of vaccination with GM-CSF gene-transduced autologous tumour cells. The S-100B serum concentration before treatment is a strong independent prognostic factor for survival, as in this study the 11 patients with low (< 0.16 microgram/l) S-100B levels were at considerably lower risk for death. All patients alive at the end of the study (n = 8) had a S-100B level within the reference range at the start of the study. At a level of 0.16 microgram/l the presence of disease could be predicted with 99% certainty for 63% of the patients. Nine patients became progressive after a stable disease. In four of them S-100 increased over 50% before clinical observation of progression, giving a lead time of more than a month in 44% of cases. In patients who acquired a status of no clinical evidence of disease after treatment, the S-100B concentration invariably decreased by more than 100%.

Application of immunohistochemistry to the diagnosis of salivary gland tumors

A panel of antibodies composed of the cytokeratins (CKs), vimentin, and actin was applied to 114 minor salivary gland tumors to evaluate its diagnostic value. The results revealed that luminal cells of intercalated duct-like structures, such as those seen in pleomorphic adenoma, basal cell adenoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma, expressed CKs 7, 8, 14, and 19. The outer cells of these structures exhibited vimentin or vimentin plus muscle-specific actin, but rarely CK14, which is seen particularly in pleomorphic adenoma, in the tubular type of basal cell adenoma, and seldom in the tubular type of adenoid cystic carcinoma. Modified myoepithelial cells of pleomorphic adenoma and myoepithelioma exhibited a variable immunoprofile. CKs 7 and 8 were also observed in acinar cell adenocarcinoma and polymorphous low-grade adenocarcinoma with vimentin in the latter. CK13 was expressed only by canalicular adenoma and mucoepidermoid carcinoma cells. This study showed that the panel of antibodies employed is effective in distinguishing among salivary gland tumors.

Cutaneous melanoma with myxoid features: twelve cases with differential diagnosis

Substantial myxoid change can occur in malignant melanoma, but its importance in primary disease has not been systematically evaluated. This report describes the clinical, microscopic, histochemical, and immunohistochemical findings in 12 patients with primary cutaneous malignant melanoma with myxoid features. The tumors presented as solitary lesions situated on the limbs (six lesions), trunk (four lesions), and head and neck (two lesions). The patients included six women and six men, whose ages ranged from 26 to 95 years, with a mean of 63 years. Breslow thickness varied from 0.48 mm to more than 12 mm, with a mean of more than 3.2 mm. Clinical follow-up for an average of 22 months showed one local recurrence, but no evidence of metastases yet. In all cases, there was a combination of myxoid and nonmyxoid areas. A minimum of 15% myxoid cross-sectional area was required for inclusion in the study, and up to 80% was observed. The pale blue mucin identified on hematoxylin and eosin staining was sensitive to hyaluronidase and positive for alcian blue in the 10 cases stained. Immunohistochemical staining was positive for S-100 in all 9 cases stained, positive for HMB-45 in 9 (90%) of 10, and negative for cytokeratin in all 9 cases in which myxoid melanoma remained in the block after previous sections. The presence of myxoid stroma did not define a biologically significant subgroup of melanoma. Only in cases with extensive (>50%) myxoid stromal effacement of the melanoma was there a major diagnostic hurdle. The diagnosis of primary cutaneous melanoma with myxoid features was seldom as problematic as metastatic myxoid melanoma. Positive S-100 stains, negative cytokeratin immunohistochemical stains, and hyaluronidase-sensitive alcian blue staining assisted in the diagnosis of this entity.

Concerted regulation of wild-type p53 nuclear accumulation and activation by S100B and calcium-dependent protein kinase C

The calcium ionophore ionomycin cooperates with the S100B protein to rescue a p53-dependent G(1) checkpoint control in S100B-expressing mouse embryo fibroblasts and rat embryo fibroblasts (REF cells) which express the temperature-sensitive p53Val135 mutant (C. Scotto, J. C. Deloulme, D. Rousseau, E. Chambaz, and J. Baudier, Mol. Cell. Biol. 18:4272-4281, 1998). We investigated in this study the contributions of S100B and calcium-dependent PKC (cPKC) signalling pathways to the activation of wild-type p53. We first confirmed that S100B expression in mouse embryo fibroblasts enhanced specific nuclear accumulation of wild-type p53. We next demonstrated that wild-type p53 nuclear translocation and accumulation is dependent on cPKC activity. Mutation of the five putative cPKC phosphorylation sites on murine p53 into alanine or aspartic residues had no significant effect on p53 nuclear localization, suggesting that the cPKC effect on p53 nuclear translocation is indirect. A concerted regulation by S100B and cPKC of wild-type p53 nuclear translocation and activation was confirmed with REF cells expressing S100B (S100B-REF cells) overexpressing the temperature-sensitive p53Val135 mutant. Stimulation of S100B-REF cells with the PKC activator phorbol ester phorbol myristate acetate (PMA) promoted specific nuclear translocation of the wild-type p53Val135 species in cells positioned in early G(1) phase of the cell cycle. PMA also substituted for ionomycin in the mediating of p53-dependent G(1) arrest at the nonpermissive temperature (37.5 degrees C). PMA-dependent growth arrest was linked to the cell apoptosis response to UV irradiation. In contrast, growth arrest mediated by a temperature shift to 32 degrees C protected S100B-REF cells from apoptosis. Our results suggest a model in which calcium signalling, linked with cPKC activation, cooperates with S100B to promote wild-type p53 nuclear translocation in early G(1) phase and activation of a p53-dependent G(1) checkpoint control.

Development of a monoclonal antibody to the aP2 protein to identify adipocyte precursors in tumours of adipose differentiation

aP2 gene product (aP2 protein) expression has been shown to be a useful diagnostic marker for identification of lipoblasts and fetal fat cells in soft tissue tumours. A monoclonal antibody was developed by a mouse spleen cell-myeloma hybridoma technique to an 18 amino acid segment of the aP2 protein and was used to investigate the immunohistochemical expression of this protein in benign and malignant tumours of adipocytic differentiation and a wide variety of other soft tissue tumours. We found that aP2 protein was expressed by lipoblasts in liposarcomas and lipoblastomas and by brown fat cells in hibernomas and normal periadrenal fat. Other benign adipose tissue tumours and benign and malignant soft tissue tumours were distinguished from liposarcoma by absence of staining for aP2 protein. Immunohistochemical identification of the aP2 protein is likely to prove a useful means of distinguishing liposarcoma from other malignant mesenchymal and epithelial neoplasms, some of which contain cells that morphologically resemble lipoblasts.

Predictive value of serum S100B for monitoring patients with metastatic melanoma during chemotherapy and/or immunotherapy

In the immunohistology of malignant melanoma the use of polyclonal antibodies against protein S100 is well established. Recently, it was shown that S100B, a subunit of the S100 protein family, is detectable in the serum of melanoma patients and correlates with the stage of the disease in patients with metastatic melanoma. In the present study, the first evaluation of a large number of treatment observations (n = 77) in 64 different patients during chemotherapy and/or immunotherapy for advanced metastatic melanoma (stage IV) is presented. All patients received treatment according to standardized protocols comprising 8 weeks of treatment followed by routine staging procedures to evaluate therapeutic outcome. In 13 patients with tumour enlargement after first-line therapy, a second-line treatment was subsequently given. S100B immunoradiometric assay (IRMA) tests were performed before, during and after treatment at scheduled time points. In the interim analysis at 4 weeks 29 of 37 (78%) patients with tumour progression during treatment showed a raised S100B level. In the final analysis at 8 weeks, 31 of these 37 patients (84%) demonstrated rising S100B values (P < 0.001). Patients who responded to treatment (stable or regressing metastatic disease) showed constant or declining S100B levels in 38 of 40 patients (95%) at the interim analysis, at 8 weeks this was further increased to 39 of 40 patients (98%; P < 0.001). Thus, the use of S100B for monitoring treatment is adequate in the majority of cases. Our observations are of great interest for therapeutic trials of adjuvant and palliative therapies as the rise of S100B levels might indicate that re-staging and/or changes in therapy strategies should be chosen.

Immunoreactivity of ductal cells with putative myoepithelial markers: A potential pitfall in breast carcinoma

The identification of an intact layer of myoepithelial cells (MECs) located between epithelial cells and the basal lamina is useful in differentiating benign breast lesions and carcinoma in situ from invasive breast carcinoma. In the present study we used three antibodies considered to be putative markers of MECs (S100 protein, muscle-specific actin [HHF-35], and smooth muscle actin [SMA]) in 100 formalin-fixed, paraffin-embedded histologic sections of breast in an attempt to compare their value in demonstrating MECs in benign breast tissue and breast carcinomas. We concluded that for identifying MECs in benign breast tissue, SMA appears to be the most reliable, followed closely by HHF-35, but S100 is very unreliable for this purpose. In breast carcinoma, all three stains showed variable cross-reactivity with myofibroblasts, being greatest with SMA. A significant number of tumor cells in ductal carcinoma, both intraductal and invasive, stain with these markers and this "cross-reactivity" is extremely high with HHF-35. Thus, immunohistochemistry should be interpreted cautiously in differentiating benign, in situ, and invasive breast neoplasms. The "cross-reactivity" also suggests the possibility of myoepithelial differentiation and/or high actin content of breast tumor cells.

Melan-A/Mart-1 expression in various melanocytic lesions and in non-melanocytic soft tissue tumours

AIMS

The purpose of this study was to test different malignant non-melanocytic tumours with the commercially available antibody Melan-A to examine its diagnostic specificity and to compare the S100, Melan-A and HMB-45 reactivity in various melanocytic lesions.

METHODS AND RESULTS

Seventy-three benign and malignant melanocytic lesions and 31 cases of non-melanocytic tumours, sarcomas, carcinomas and carcinoids, were selected. Immunohistochemical staining of paraffin sections, following a high temperature antigen unmasking technique, was performed. Melan-A stains junctional and dermal melanocytes in all benign melanocytic lesions with the exception of neuro-naevoid areas. The epithelioid and the spindle cells in malignant melanomas did not show considerable difference in their Melan-A reactivity. The predominantly spindle cell type mucosal melanomas contained more Melan-A-positive cells than HMB-45-positive cells and similar results were observed in metastatic malignant melanomas. In desmoplastic melanomas the positivity of Melan-A was not consistent. None of the sarcomas, carcinomas and carcinoids expressed Melan-A. Almost all soft tissue tumours, except for two malignant gastrointestinal stromal tumours, were unreactive for HMB-45. These two cases did not react with Melan-A antibody.

CONCLUSIONS

Melan-A is a useful additional marker to differentiate non-melanocytic tumours from primary or metastatic melanoma. In melanocytic lesions the Melan-A staining pattern is similar to S100, but seems to be more specific. In desmoplastic melanomas, however, the variable Melan-A staining further necessitated detailed histological examination and the use of the S100 reaction.

Calcium-dependent interaction of S100B with the C-terminal domain of the tumor suppressor p53

In vitro, the S100B protein interacts with baculovirus recombinant p53 protein and protects p53 from thermal denaturation. This effect is isoform-specific and is not observed with S100A1, S100A6, or calmodulin. Using truncated p53 proteins in the N-terminal (p53(1-320)) and C-terminal (p53(73-393)) domains, we localized the S100B-binding region to the C-terminal region of p53. We have confirmed a calcium-dependent interaction of the S100B with a synthetic peptide corresponding to the C-terminal region of p53 (residues 319-393 in human p53) using plasmon resonance experiments on a BIAcore system. In the presence of calcium, the equilibrium affinity of the S100B for the C-terminal region of p53 immobilized on the sensor chip was 24 +/- 10 nM. To narrow down the region within p53 involved in S100B binding, two synthetic peptides, O1(357-381) (residues 357-381 in mouse p53) and YF-O2(320-346) (residues 320-346 in mouse p53), covering the C-terminal region of p53 were compared for their interaction with purified S100B. Only YF-O2 peptide interacts with S100B with high affinity. The YF-O2 motif is a critical determinant for the thermostability of p53 and also corresponds to a domain responsible for cytoplasmic sequestration of p53. Our results may explain the rescue of nuclear wild type p53 activities by S100B in fibroblast cell lines expressing the temperature-sensitive p53val135 mutant at the nonpermissive temperature.

Sustentacular cells in pulmonary neuroendocrine tumours

AIMS

To determine the prevalence of sustentacular cells across the range of pulmonary neuroendocrine tumours: typical and atypical carcinoid tumours and large cell and small cell neuroendocrine carcinomas.

METHODS AND RESULTS

Sustentacular cells were sought in 80 pulmonary neuroendocrine tumours by immunolabelling for S100 protein, nerve growth factor receptor and glial fibrillary acidic protein. Intratumoural macrophages and Langerhans cells were identified with the KP 1 (CD68) and CD1A antibodies. S100-positive sustentacular cells were present in 25 of 30 typical carcinoids, 200 of 25 atypical tumours, six of 10 large cell carcinomas and six of 15 small cell lesions. They were most numerous in the typical carcinoids but very few in the small cell carcinomas, their prevalance being clearly related to grade of differentiation and, in particular, to the degree of architectural organization.

CONCLUSIONS

Sustentacular cells are often found in pulmonary neuroendocrine tumours, especially better-differentiated lesions with a well-developed architecture. their prevalence clearly reflecting the degree of structural organization. Whether their prevalence is a useful prognostic indicator within a particular group of such tumours, such as the atypical carcinoids or the large cell carcinomas, as appears to be the case with paragangliomas, is unclear.