Thomsen-Friedenreich and its precursor (Tn) antigen expression in normal skin and in benign cutaneous tumours: a marker for sebaceous differentiation

Sebaceous Carcinoma of the Eyelid

BACKGROUND

Periocular sebaceous carcinoma (PSC) is a rare but aggressive neoplasm that tends to clinically and histopathologically mimic other conditions. PSC can be challenging to diagnose using histomorphology alone given its overlap with 2 more common tumors that occur in this area (basal cell carcinoma [BCC] and squamous cell carcinoma [SCC]). Use of immunohistochemistry can help resolve this differential diagnosis.

METHODS

A review of the literature was performed, focusing on the epidemiology, morphology, and immunohistochemical features of PSC.

RESULTS

The most useful immunostains in the differential diagnosis of PSC are epithelial membrane antigen, Ber-Ep4, androgen receptor (AR), and adipophilin. To discern PSC from BCC, one should use EMA, Ber-Ep4, AR, and adipophilin, whereas discerning PSC from SCC can be achieved by evaluating AR and adipophilin. In addition, p53 and ERBB2 (formally known as HER2/neu) are other potentially useful immunohistochemical markers for the differential diagnosis of PSC.

CONCLUSIONS

Use of new immunohistochemical techniques, as well as the elucidation of molecular alterations, such as the presence of ERBB2 amplification, will advance our understanding of PSC.

Topics in histopathology of sweat gland and sebaceous neoplasms

This article reviews several topics regarding sweat gland and sebaceous neoplasms. First, the clinicopathological characteristics of poroid neoplasms are summarized. It was recently reported that one-fourth of poroid neoplasms are composite tumors and one-fourth are apocrine type lesions. Recent progress in the immunohistochemical diagnosis of sweat gland neoplasms is also reviewed. CD117 can help to distinguish sweat gland or sebaceous tumors from other non-Merkel cell epithelial tumors of the skin. For immunohistochemical differential diagnosis between sweat gland carcinoma (SGC) other than primary cutanesous apocrine carcinoma and skin metastasis of breast carcinoma (SMBC), a panel of antibodies may be useful, including p63 (SGC⁺ , SMBC^- ), CK5/6 (SGC⁺ , SMBC^- ), podoplanin (SGC⁺ , SMBC^- ) and mammaglobin (SGC^- , SMBC⁺ ). Comparison of antibodies used for immunohistochemical diagnosis of sebaceous carcinoma (SC) suggests that adipophilin has the highest sensitivity and specificity. Some authors have found that immunostaining for survivin, androgen receptor and ZEB2/SIP1 has prognostic value for ocular SC, but not extraocular SC. In situ SC is rare, especially extraocular SC, but there have been several recent reports that actinic keratosis and Bowen's disease are the source of invasive SC. Finally, based on recent reports, classification of sebaceous neoplasms into three categories is proposed, which are sebaceoma (a benign neoplasm with well-defined architecture and no atypia), borderline sebaceous neoplasm (low-grade SC; an intermediate tumor with well-defined architecture and nuclear atypia) and SC (a malignant tumor with invasive growth and evident nuclear atypia).

Sebaceous carcinoma: an immunohistochemical reappraisal

The rates of distant metastases and tumor death in sebaceous carcinoma (SC) have been reported to be higher than those of other cutaneous carcinomas, such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), regardless of whether they occur in ocular or extraocular regions. Therefore, strict differentiation of SC from SCC and BCC is required. In this article, we report immunohistochemical findings of SC and compare these data to those of SCC, BCC, and sebaceoma. An immunohistochemical study was performed using 7 antibodies [anti-carcinoembryonic antigen (CEA), anti-epithelial membrane antigen (EMA), anti-CA15-3, anti-CA19-9, anti-androgen receptor (AR), anti-epithelial antigen (Ber-EP4), and anti-adipophilin (ADP)] on 35 cases of SC (16 cases in ocular and 19 cases in extraocular regions) and 10 cases of each SCC (5 cases in ocular and 5 cases in extraocular regions), BCC (5 cases in ocular and 5 cases in extraocular regions), and sebaceoma (no cases arose on the eyelids). In summary, the typical immunophenotypes of SC were EMA+, CA15-3+, AR+, Ber-EP4-, and ADP+; those of sebaceoma were CEA-, EMA+, Ber-EP4-, and ADP+; those of SCC were CEA-, EMA+, CA19-9-, AR-, Ber-EP4-, and ADP-; and those of BCC were CEA-, EMA-, CA15-3-, Ber-EP4+, and ADP-. Other antibody tests for each neoplasm were positive in about half of the cases. The detection of AR and ADP was useful for differentiating SC from SCC, whereas the determination of EMA, CA15-3, Ber-EP4, and ADP was valuable in differentiating SC from BCC.

Immunohistochemical expression of D2-40 in benign and malignant sebaceous tumors and comparison to basal and squamous cell carcinomas

The diagnosis of sebaceous carcinoma presents an important challenge to both clinicians and pathologists, as many cases are initially misdiagnosed both clinically and histopathologically, potentially leading to adverse medical and legal outcomes. The distinction of sebaceous carcinoma from benign sebaceous proliferations and other tumors is therefore of utmost importance, and immunohistochemistry may be useful in this differential. We studied the expression of D2-40 (podoplanin) by immunohistochemistry to determine if it can aid in this differential diagnosis and to evaluate the possibility of lymphangiogenesis in sebaceous carcinoma. A total of 36 cases of sebaceous lesions, including 16 sebaceous carcinomas, 7 sebaceous adenomas, 6 sebaceomas, and 7 cases of normal glands and sebaceous hyperplasia, and 17 cases of basal cell carcinoma and 10 cases of squamous cell carcinoma, were also examined. We found no significant increase in tumor lymphangiogenesis by semiquantitative scoring of lymphovascular density per square millimeter of tumoral/peritumoral stroma in sebaceous carcinoma versus benign sebaceous proliferations. However, D2-40 staining showed a different pattern in the benign tumors, which were positive only in the basaloid cells (most pronounced in sebaceoma), versus sebaceous carcinoma, which was either negative or focally positive in a haphazard pattern in most cases, although some cases of basaloid sebaceous carcinomas showed strong positivity. We also found D2-40 to be only weakly and focally positive in basal cell carcinoma and weakly to moderately positive in squamous cell carcinoma, which showed increased staining with decreased differentiation. Therefore, overall, D2-40 is, of limited diagnostic utility in sebaceous lesions but may be useful in distinguishing sebaceoma and basaloid sebaceous carcinoma from basal cell carcinoma.

Analysis of Recombinant CD24 Glycans by MALDI-TOF-MS Reveals Prevalence of Sialyl-T Antigen

CD24 is a glycosyl-phosphatidyl-inositol linked glycoprotein expressed in a broad range of cell types and is heavily glycosylated. It has been found to be over expressed in cancers and tumors and is also a costimulatory molecule. Therefore, this study was carried out to define the structures of the carbohydrates associated with the CD24 recombinant protein. The CD24 glycoprotein's oligosaccharides were released by chemical and enzymatic means prior to being analyzed by MALDI-TOF-MS. The results obtained showed that CD24 is both N- and O-glycosylated. The major oligosaccharides were found to be Neu5Acα-2,3/6Galβ-1,3GalNAc, NeuAc(2)Gal β-1,3GalNAc(1) (O-glycans), GalNAc(2)GlcNAc(2)Man(3)Fuc(1), Gal(1)GalNAc(2)GlcNAc(2)Man(3)Fuc(1), and Gal(2)GalNAc(2)GlcNAc(2)Man(3)Fuc(1) (N-glycans). The results showed that Neu5Acα-2,3/6Galβ-1,3GalNAc (sialyl-tumor antigen, sT), a cancer-associated carbohydrate, was the most abundant glycan associated with CD24. This result raised the intriguing possibility that CD24 may be a major carrier of the sialyl-T abundantly found in cancer cells.

Immunohistochemical differentiation of extra-ocular sebaceous carcinoma from other skin cancers

We performed an immunohistochemical study using routinely processed formalin-fixed and paraffin-embedded tissue specimens from 26 cases of extra-ocular sebaceous carcinoma (EOSC) and eight easily available antibodies. They were polyclonal anti-carcinoembryonic antigen (CEA) antibody, monoclonal anti-CEA antibody, anti-breast carcinoma associated antigen-225 antibody (CU18), anti-CA15.3 antibody (CA15.3), anti-CD15 antibody (CD15), anti-breast carcinoma associated antigen antibody (B6.2), anti-gross cystic disease fluid antigen-15 antibody (GCDFP15) and anti-Thomsen-Friedenreich antigen antibody (TFA). Squamous cell carcinoma, porocarcinoma, syringomatous carcinoma, malignant clear cell hidradenoma, apocrine adenocarcinoma, and extramammary Paget's disease with underlying adenocarcinoma were used as controls. EOSC was positive for CU18 and CA15.3 in most cases, and for CD15 in a few cases. Squamous cell carcinoma of the skin was positive for CA15.3 in only one case. Porocarcinoma, syringomatous carcinoma and malignant clear cell hidradenoma were positive for CEA, CU18, CA15.3, and B6.2 in most cases. Apocrine adenocarcinoma and extramammary Paget's disease with underlying adenocarcinoma were positive for CEA, CU18, CD15, GCDFP15, CA15.3, and B6.2 in most cases. TFA was positive not only in EOSC but also in other skin cancers. Immunohistochemical examinations using these seven of eight antibodies except for TFA and routinely processed formalin-fixed and paraffin-embedded tissue specimens are beneficial in differentiating EOSC from other skin cancers.

Cytokeratin 5/6 Immunostaining in Cutaneous Adnexal Neoplasms and Metastatic Adenocarcinoma

The differentiation of primary cutaneous adnexal neoplasms (CANs) from dermal-based metastatic lesions can be difficult. Cytokeratin 5/6 (CK 5/6) has a relatively limited expression profile, being relatively specific for mesothelium and other "pavement" type epithelium such as squamous epithelium. To date, the degree and distribution of CK 5/6 expression in cutaneous neoplasms has not been extensively studied. We speculate that since most of CANs arise from similar epithelium, they should express CK 5/6 and, therefore, CK 5/6 could potentially be helpful in distinguishing these lesions from most of metastatic neoplasms, which usually do not express this marker. Formalin-fixed, paraffin-embedded tissue sections from 228 previously classified CANs and 27 metastatic adenocarcinomas (17 breast, 4 colon, 2 prostate, 2 ovary, 1 lung, and 1 esophagus) were immunostained with anti-CK 5/6. Anti-CK 5/6 labeled 2 of 2 proliferating trichilemmal tumors, 6 of 6 poromas, 4 of 5 hydrocystomas, 10 of 10 cylindromas, 10 of 10 eccrine acrospiromas, 8 of 10 pilomatricoma, 10 of 10 nevus sebaceus, 9 of 9 desmoplastic trichoepitheliomas, 7 of 7 nevus sebaceus with basal cell carcinomas, 10 of 10 pilar cysts, 14 of 14 trichilemmomas, 10 of 10 syringomas, 6 of 7 chondroid syringomas, 10 of 10 hidradenoma papilliferum, 9 of 9 sebaceus adenomas, 3 of 3 microcystic adnexal carcinomas, 10 of 10 eccrine spiradenomas, 4 of 4 syringocystadenoma papilliferum, 3 of 5 ocular sebaceous carcinomas, 28 of 28 basal cell carcinomas, 16 of 16 trichoepitheliomas, and 33 of 33 trichoepitheliomas with basal cell features. By contrast, 9 of 27 metastatic adenocarcinomas stained positively, although only two of these stained strongly. Cumulatively, CK 5/6 was expressed by most (97%) of CANs, while only 33% of metastatic adenocarcinomas showed positive expression. The sensitivity of this marker in the malignant lesions (other than basal cell carcinoma) is 78%, while the specificity is 67%. If all lesions are considered, the sensitivity increases to 97%. Therefore, CK 5/6 may prove to be a useful adjunct marker in distinguishing CANs from metastatic lesions.

Sebaceous carcinoma and the T-antigen

Carcinomas of sebaceous glands are uncommon. They are traditionally classified into ocular and extraocular sebaceous carcinomas (SC). Ocular SC tend to be more common and more aggressive than extraocular SC. However, the latter can occasionally follow a fatal course. Histologically, SC should be classified into 1) SC in situ; 2) SC, infiltrating, low-grade with or without pagetoid spread; 3) SC, infiltrating, high-grade, with or without pagetoid spread; and 4) SC with extraocular and extracutaneous involvement, including metastases. Immunohistochemistry plays a minor role in the diagnosis of SC. Thomsen-Friedenreich (T) antigen can be a helpful tool in differentiating SC (strong T-antigen reactivity in basaloid cells) from other mimicking neoplasms (basaloid cells are T-antigen negative). The histologic differential diagnosis, pathogenesis, and management of SC are reviewed.

Thomsen-Friedenreich (T) antigen: a possible tool for differentiating sebaceous carcinoma from its simulators

The Thomsen-Friedenreich (T) antigen is a cryptic glycoprotein, referred to as tumor antigen or cancer-associated antigen because it is absent or masked by some carbohydrates in normal tissues, but present in many human cancers. The latter include gastrointestinal, lung, pancreatic, mammary, and some ovarian carcinomas. Cancer cells frequently undergo incomplete glycosylation resulting in the appearance of precursor structures that normally would be absent like the case with the T antigen. T antigen can be detected by several different reagents including monoclonal antibodies and several plant lectins-e.g., Arachis hypogea (peanut agglutinin). The aim of the current study was to evaluate the expression of T antigen in sebaceous carcinoma and to compare it with its simulators. The authors studied the immunohistochemical expression of T antigen in 45 skin biopsy and excisional specimens obtained from the archives of their dermatopathology laboratories, including 8 cases of sebaceous carcinoma, 15 cases of sebaceous adenoma, 9 cases of sebaceoma, 1 case of basal cell carcinoma with sebaceous differentiation, and 12 cases of basal cell carcinoma with cytologic atypia. Sebaceous carcinoma was unique in expressing a strong, diffuse cytoplasmic T antigen reactivity (7 of 8 cases) along the immature basaloid cells and the intermediate cells. However, sebaceous adenoma, sebaceoma, and basal cell carcinomas expressed negative reaction in the basaloid cells and mild reactivity in the intermediate cells. Mature sebocytes showed a strong reaction in all cases. The authors concluded that T antigen expression may be a helpful tool in differentiating sebaceous carcinoma from other sebaceous lesions that may simulate it histologically.

Establishment and characterization of an immortalized human sebaceous gland cell line (SZ95)

Human facial sebaceous gland cells were transfected with a PBR-322-based plasmid containing the coding region for the Simian virus-40 large T antigen. The resulting proliferating cell cultures have been passaged over 50 times to date, have been cloned, and show no signs of senescence after 4&DF;1 2 y in vitro, whereas normal human sebocytes can only be grown for three to six passages. The immortalized transfected cells, termed SZ95, expressed the Simian virus-40 large T antigen and presented an hyper-diploid-aneuploid karyotype with a modal chromosome number of 64.5. The SZ95 cell line exhibited epithelial, polymorphous characteristics with different cell sizes of up to 3.25-fold during proliferation and 6-fold at confluence, showing numerous cytoplasmic lipid droplets. The cells showed large cytoplasm profiles with abundant organelles, including vacuoles and myelin figures which indicated lipid synthesis. Lack of or only few desmosomal areas were observed. SZ95 cells expressed molecules typically associated with human sebocytes, such as keratins 7, 13, and 19, and several proteins of the polymorphous epithelial mucin family. Functional studies revealed synthesis of the sebaceous lipids squalene and wax esters as well as of triglycerides and free fatty acids, even after 25-40 passages; active lipid secretion; population doubling times of 52.4 +/- 1.6 h; reduced growth but maintenance of lipid synthesis under serum-free conditions; and retrieval of cell proliferation after addition of 5alpha-dihydrotestosterone. Retinoids significantly inhibited proliferation of certain SZ95 cell clones in the expected magnitude 13-cis-retinoic acid > all-trans-retinoic acid > > acitretin. Thus SZ95 is an immortalized human sebaceous gland cell line that shows the morphologic, phenotypic and functional characteristics of normal human sebocytes.

Differential expression of the cancer associated antigens T (Thomsen-Friedenreich) and Tn to the skin in primary and metastatic carcinomas

AIM

To study the immunohistochemical expression of the Thomsen-Friedenreich antigen (T) and its precursor, Tn, in the skin in various cancers.

METHODS

T and Tn antigens were studied with monoclonal antibodies in 91 primary premalignant and malignant lesions, 13 cases of Paget's disease, and 26 carcinomas metastatic to the skin. The material had been collected over a 10 year period, formalin fixed, and paraffin embedded. Diagnoses had been made after examination of standard histological sections, supplemented when needed by appropriate immunohistochemical staining.

RESULTS

21% and 29% of the primary cutaneous premalignant and malignant epithelial tumours expressed the Tn and T antigens, respectively. By contrast, 81% of metastatic carcinomas to the skin were Tn positive, while only 23% of them expressed the T antigen. All cases of Paget's disease were Tn positive but only 15% of them expressed the T antigen. The 21 nonepithelial tumours (including melanomas) were as a rule unreactive.

CONCLUSIONS

The accumulation of the precursor (Tn) antigen in tumours metastasising to the skin highlights the incomplete glycosylation of carbohydrate antigens occurring in these tumours. The predominant Tn versus T antigen expression appears to be a useful immunohistochemical feature which may aid in the differentiation of primary cutaneous carcinomas from metastatic tumours.