Chromogranin A expression correlates with tumour cell type and prognosis in signet ring cell carcinoma of the stomach.

AIMS: To investigate neuroendocrine (NE) differentiation in gastric signet ring cell carcinoma (SRCC) using chromogranin A (CgA) as an indicator of a well-differentiated NE phenotype and to determine its relationship to cell type, stage and prognosis. METHODS AND RESULTS: 102 SRCCs were categorized into five subtypes according to the predominant cell type in the World Health Organization classification. 38 cases (37.3%) showed focal or diffuse CgA positivity. The positive cells were mostly histiocytoid and eosinophilic SRCC cells and some were classical SRCC cells. Small cell and anaplastic-type SRCC cells were only rarely immunopositive. There was no significant relationship between CgA expression and the extent of invasion or presence of metastasis. However, a significant positive correlation existed between CgA positivity and favourable prognosis, with a tendency for greater positivity to be associated with better overall survival. Multivariate analysis showed expression of CgA to be an independent prognostic factor. CONCLUSION: CgA expression is restricted to certain tumour cell types and may help to predict prognosis in gastric SRCCs.

Proliferation and apoptosis of tumour cells before and after neoadjuvant therapy for high-grade extremity sarcomas: divergent associations with tumour response and prognosis.

AIMS: To evaluate proliferation and apoptosis in high-grade sarcomas of the extremities before and after preoperative radio-hyperthermo-chemotherapy (RHC) and to determine the relationship between these parameters and treatment outcomes. METHODS AND RESULTS: Pre- and post-RHC specimens of 41 soft tissue and bone tumours were immunohistochemically stained for minichromosome maintenance protein (MCM) 2 and caspase 3 as proliferation and apoptosis markers, respectively, based on a preliminary study comparing them with conventional markers. Indices were calculated as a percentage of positive cells by counting tumour cells in the most frequently labelled areas. MCM2, caspase 3 and MCM2/caspase 3 (growth) indices were 45.3 +/- 21.9%, 4.1 +/- 7.1% and 82.9 +/- 104.5, respectively, in pre-RHC specimens and 35.4 +/- 30.8%, 39.2 +/- 34.6% and 5.3 +/- 11.7, respectively, in post-RHC specimens. Response scores showed positive correlation with pre-RHC MCM2 and post-RHC caspase 3 indices, inverse correlation with post-RHC MCM2 and post-RHC growth indices and no correlation with prognosis. Multivariate analysis revealed high pre-RHC MCM2 and high post-RHC growth indices as significant unfavourable prognostic factors. CONCLUSIONS: High proliferative activity in untreated sarcoma may predict good response to neoadjuvant therapy, but poor prognosis, whereas a high growth index, i.e. high proliferation:apoptosis ratio in a post-neoadjuvant therapy tumour specimen may indicate poor response and poor prognosis.

Nodal T/NK-cell lymphoma of nasal type: a clinicopathological study of six cases.

AIMS: To investigate the clinicopathological features of six unusual cases of nodal CD56+ and Epstein-Barr virus (EBV)+ T/natural killer (NK)-cell lymphoma, a putative nodal counterpart of nasal NK/T-cell lymphoma (nodal T/NK-cell lymphoma of nasal type) in comparison with nasal NK/T-cell lymphoma with secondary lymph node involvement (n = 24) and peripheral T-cell lymphoma (PTCL) of cytotoxic molecule (CTM)+ and EBV+ type (n = 21). METHODS AND RESULTS: All cases of nodal T/NK-cell lymphoma of nasal type exhibited diffuse infiltration of pleomorphic medium-sized to large tumour cells, reminiscent of those in CTM+ EBV+ PTCL. The tumour cells had a typical phenotype of nasal NK/T-cell lymphoma: CD2+, CD3epsilon+, CD4-, CD5-, CD56+, T-cell intracellular antigen-1+, granzyme B+, perforin+ and EBV+. However, four of six cases demonstrated clonal T-cell receptor gamma-gene rearrangement on polymerase chain reaction analysis, unlike nasal NK/T-cell lymphoma. Comparison of clinical parameters and overall survival among the three groups demonstrated only minor differences. CONCLUSIONS: Nodal T/NK-cell lymphoma may occupy the grey zone between extranodal nasal-type NK/T-cell lymphoma and nodal CTM+ PTCL in a spectrum of NK to T-cell lymphomas that are EBV+. The close relationship between NK/T-cell lymphomas and cytotoxic T-cell lymphomas was also substantiated.

MUM1/IRF4 expression as a frequent event in mature lymphoid malignancies.

MUM1/IRF4 is a myeloma-associated oncogene transcriptionally activated as a result of t(6;14)(p25,q32) chromosomal translocation and by virtue of its juxtaposition to the immunoglobulin heavy chain gene (IgH) locus. When this oncogene becomes non-functional, no activated B/T lymphocytes and Ig secreting plasma cells are observed, suggesting that MUM1/IRF4 is crucial for lymphoid development. Its expression was analyzed in both reactive lymphoid and lymphoma tissues by means of an immunohistochemical technique using specific goat antiserum against MUM1/IRF4. This analysis detected a 50 kDa MUM1 product whose localization was restricted to the nuclei of the lymphocytes. The MUM1+ cells in reactive lymph nodes were found to consist of plasma cells and a small fraction (approximately 7.9%) of B cells harboring CD20+CD38+, which were located in the light zone of the germinal center. MUM1 expression in peripheral blood B/T lymphocytes was upregulated by mitogenic stimuli, suggesting that MUM1 positivity represents the activated state of the B/T cells. In B cell non-Hodgkin's lymphoma (NHL), MUM1 expression was observed in 73.2% (30/41) of diffuse large B cell lymphoma (DLBCL), 20% (1/5) of marginal zone lymphoma (MZL) and 43% (3/7) of small lymphocytic lymphoma (SLL) cases, whereas it was not seen in any cases of mantle cell lymphoma (MCL) or follicle center lymphoma (FCL). Also, MUM1 was stained at high intensity in various types of T cell lymphomas including adult T cell leukemia/lymphoma (ATL/L) and anaplastic large cell lymphoma (ALCL) and in the majority of Hodgkin's diseases. Our results suggest that a major proportion of lymphomas comprise either physiologically or aberrantly activated neoplastic lymphocytes expressing the MUM1 protein.

Human seminal plasma beta-microseminoprotein: its purification, characterization, and immunohistochemical localization.

beta-Microseminoprotein was very efficiently purified from human seminal plasma with only three steps including DEAE-Sephacel and Zinc-chelate Sepharose CL-6B column chromatography. The purified protein was a non-glycoprotein with a molecular weight (M(r)) of 19,000 and 17,000 on gel filtration and reduced SDS-PAGE, respectively. The protein gave six bands from M(r) 15,600 to 25,500 on non-reduced SDS-PAGE. The characterization including the molecular weight, amino acid sequence of N-terminus and concentrations in various body fluids is discussed. Furthermore, the immunohistochemical localization of the protein among various human tissues is demonstrated.

Clinical and functional significance of WHO classification on human thymic epithelial neoplasms: a study of 146 consecutive tumors.

We examined the clinical and functional significance of histologic classification of thymic epithelial neoplasms proposed by the World Health Organization (WHO), based on an analysis of 146 consecutive tumors derived from 141 patients and 47 normal thymuses derived from children ranging in age from 1 to 9 years. Invasive tumors were seen in 12.5%, 38.6%, 40.0%, 69.4%, 80.0%, and 100% of type A, AB, B1, B2, B3, and C primary tumors, respectively. All of six recurrent or metastatic lesions were type B2 tumors. Myasthenia gravis was associated in 0%, 6.8%, 40.0%, 55.6%, 10.0%, and 0% in patients with type A, AB, B1, B2, B3, and C tumors, respectively. The average number (x10(6)) of tumor-associated CD4+CD8+ cells present in 1 g of tumor tissue was 1.5, 391.1, 1041.7, 333.9, 24.5, and 0.2 in type A, AB, B1, B2, B3, and C, respectively, and it was 1168.2 in the normal thymuses. Thus, type B1 tumor retained the function to induce CD4+CD8+ double-positive cells at a level comparable to that of the normal thymic cortical epithelial cells, followed by type AB and type B2 tumors. Type A and B3 tumors had this function at a barely detectable level, and type C tumor was nonfunctional. WHO histologic classification was shown to reflect the clinical features and the T-cell-inducing function of thymic epithelial tumors.

Expression of 20 KD homologous restriction factor of complement on myocardial cells: an immunohistochemical study using acetone-fixed and paraffin-embedded tissues.

Expression of 20 KD homologous restriction factor of complement (HRF20) (CD59) in normal human heart was immunohistochemically examined with monoclonal antibody (MAb) 1F5. HRF20 was clearly demonstrated on the cell surface membrane and intercalated discs of myocardial cells throughout the ventricular walls. Therefore, this factor may protect normal cardiomyocytes from complement deposition, which has been demonstrated on infarcted cardiomyocytes. Expression of HRF20 was also observed on endothelial cells of the endocardium and on blood vessels, including arteries, capillaries, and veins, and on the Schwann-cell sheath of peripheral nerve fibers. In the present study, we found that the epitopes of HRF20 were well preserved for immunohistochemistry even in acetone-fixed and paraffin-embedded tissues, as well as in frozen tissues that have been conventionally used for HRF20. This method using paraffin sections allows for easier staining and greater accuracy in histological examination.

Immunohistochemical localization of Zn-alpha 2-glycoprotein in normal human tissues.

The Zn-alpha 2-glycoprotein (Zn-alpha 2-GP) is present at a high concentration in the seminal plasma and at significant levels in other human body fluids. Its precise localization, however, has remained unclear, as well as its physiological and pathological significance. The present study reports the immunohistochemical localization of this protein in normal adult human tissues. Localization of the reactive product to anti-human plasma Zn-alpha 2-GP antibody was demonstrated in the following cells: luminal and basal cells of the prostate gland, luminal epithelial cells of the acini and of some ducts of the mammary glands, luminal cells of the secretory portion of the eccrine and apocrine sweat glands, serous cells of the salivary, tracheal, and bronchial glands, acinar cells of the esophageal glands, exocrine acinar cells of the pancreas, hepatocytes of the liver, and epithelial cells of the proximal and distal tubules in the kidney. The present results suggest that Zn-alpha 2-GP exerts some unknown but fairly widespread exocrine function and may be produced in the various epithelial cells tested. Hepatocytes are also suggested to be a source of the protein in the blood plasma.

Gastric syphilis: polymerase chain reaction detection of treponemal DNA in pseudolymphomatous lesions.

Syphilis is an unexpected diagnosis in the stomach. To establish the diagnosis, evidence of Treponema pallidum in the gastric lesion is necessary. However, it is sometimes difficult to prove the presence of the organisms by conventional methods. The authors describe two cases of early gastric syphilis with pseudolymphomatous histology in which T pallidum gene was detected by the polymerase chain reaction (PCR) using paraffin biopsy sections. The gastric lesion of each case endoscopically and histologically simulated that of malignant lymphoma. However, no clonality was proved by immunohistochemistry or PCR gene rearrangement analysis. No spirochetal organisms were detected with certainty by Warthin-Starry silver stain, whereas the organisms were shown by immunofluorescent stain in one patient. A PCR study showed the treponemal DNA in both patients, and its validity was supported by a direct sequencing and a restriction enzyme digestion. Positive results of serological tests for syphilis and regression of the lesions after antisyphilitic treatment were confirmatory of the diagnosis. Gastric syphilis should be considered as a differential diagnosis when an atypical lymphoid infiltrate fails to show monoclonality. The present PCR method would be helpful in showing T pallidum using routinely processed small biopsy specimens as the tissue source.

Mediastinal malignant epithelioid schwannoma.

A case of mediastinal malignant epithelioid schwannoma (MES) is reported. The tumor probably arose in the vagal nerve, and the trachea was involved. A few months after excision of the primary tumor, multiple metastases appeared in lung, cervical spine, and neck lymph nodes. Microscopically, the tumor showed a highly cellular area resembling melanoma or carcinoma. Immunolabeling was done for S-100 protein, keratin, and melanoma-associated antigen. Examination of the entire lesion and in situ characteristics of the tumor involving the vagal nerve were helpful in making the correct diagnosis. Mediastinal MES, to our knowledge, has not been reported to date in the English-language medical literature.

Differential diagnosis of thymic carcinoma and lung carcinoma with the use of antibodies to cytokeratins.

There are few specific pathologic findings that can be relied on to distinguish primary thymic carcinomas from lung carcinomas with mediastinal extension or showing metastasis to the anterior mediastinum. The immunohistochemical reactivity on frozen sections of thymic carcinomas and lung carcinomas, which are histologically similar to each other, was examined with the use of monoclonal antibodies to cytokeratins 7 and 13. Among keratinizing squamous cell carcinomas, all thymic carcinomas reacted with antibody specific for cytokeratin 7 (9/9, 0%), whereas no staining reaction was seen in lung carcinomas (0/5, 0%) (p < 0.01). This finding can be used as a diagnostic aid in primary thymic keratinizing squamous cell carcinomas to expedite treatment and prognosis. Cytokeratin 7 and cytokeratin 13 monoclonal antibodies reacted with almost all cases of thymic carcinoma. Applications of monoclonal antibodies specific for certain cytokeratins, especially 7 and 13, may be helpful in the diagnosis of other subtypes of thymic carcinomas.

Detection of SYT-SSX fusion transcript in synovial sarcoma using archival cytologic specimens.

Identification of the SYT-SSX fusion transcript can be a useful diagnostic aid for synovial sarcoma. However, there is no report on the detection of the specific transcript in archival cytologic specimens. We performed a rapid reverse transcription-polymerase chain reaction assay to detect the fusion transcript using such specimens as RNA sources and compared its usefulness with the assay using formalin-fixed paraffin-embedded histologic specimens. Eleven cytologic and 12 histologic specimens stored for 0.1 to 20 years were selected from 9 patients. The SYT-SSX transcript was identified in 10 (91%) of 11 of cytologic and 9 (75%) of 12 histologic cases. One of the transcript-positive cytologic cases was obtained by fine-needle aspiration. SYT-SSX1 fusion was found in 4 patients and SYT-SSX2 in 5. Cytologic specimens will be an excellent RNA source for the reverse transcription-polymerase chain reaction diagnosis of synovial sarcoma with a sensitivity of more than 90%, comparable to that in frozen materials. Histologic materials also may be useful when cytologic or frozen materials are not available.

Nonneoplastic and nonhyperplastic thymus in myasthenia gravis. An immunohistochemical study with double immunoenzymatic labeling of basement membrane and cellular components.

Histologically normal thymus (type A) in patients with myasthenia gravis (MG) was immunohistochemically compared with hyperplastic MG thymus (type B) and normal non-MG thymus. In formalin-fixed, paraffin-embedded sections of ten type A, ten type B, and eight non-MG cases, the thymic epithelium and other cellular components were stained in conjunction with the basement membrane by a double immunoenzymatic method. This technique demonstrated a moderate architectural disturbance in type A thymus, with distended perivascular space (PVS), elongated medullary epithelium, and disrupted basement membrane. These changes were more prominent in type B thymus but were minimal to lacking in non-MG thymus. Compared with those in non-MG thymus, the myoid cells in MG thymuses of both types tended to cluster around the Hassall's corpuscles, with a slight decrease in number in type B but not in type A. B-lymphocytes were present in type B, type A, and non-MG thymuses in that order of abundance; the cells were confined to the medullary parenchyma in the non-MG group but were numerous both in the PVS and medulla in the MG groups. T-lymphocytes were increased in the expanded PVS of type A and B MG thymuses. The number of interdigitating reticulum cells was similar in the three groups, but the cellular distribution was more dispersed in MG thymuses of both types. These findings, although previously described in type B thymus, have not been well recognized in type A thymus. They support the view that a common abnormality (presumably chronic thymitis), differing in degree only, underlies MG thymuses regardless of the presence of follicular hyperplasia.

p53 protein expression and p53 gene mutation in thymic epithelial tumors. An immunohistochemical and DNA sequencing study.

p53 protein expression in 34 thymic epithelial tumors was examined immunohistochemically, and p53 gene mutation was detected in selected cases by DNA sequencing, using formalin-fixed and paraffin-embedded tissues. The tumors comprised 12 noninvasive thymomas, 9 invasive/metastatic thymomas, and 13 thymic carcinomas. All the tumors were immunoreactive for p53 protein. The p53-positive tumor cells in noninvasive thymoma were less than 10% (low expressor) in 7 cases and 10% to 50% (moderate expressor) in 5 cases. In invasive/metastatic thymoma, two were low expressors and seven were moderate expressors. In thymic carcinomas, there were nine moderate expressors and four high expressors (with > 50% positive cells). There was significant difference in p53 protein immunopositivity between thymic carcinoma and each of the noninvasive or invasive/metastatic thymomas. The DNA sequencing study confirmed the presence of p53 gene point mutation in all 10 cases examined, including three low expressors. These results suggest that p53 gene mutation is an early event in thymic tumorigenesis, and the p53 protein-positive cells increase with the progression of the tumor. Immunostaining reactivity of p53 may be a useful adjunct to differentiate thymic carcinoma from thymoma.

Immunoreactivity of a new CD5 antibody with normal epithelium and malignant tumors including thymic carcinoma.

CD5, first recognized on subsets of lymphocytes, also is detected in thymic carcinoma but not in thymoma or other malignant tumors. We studied CD5 expression in 73 cases of malignant tumors of various organs, 22 cases of thymoma, and 7 cases of thymic carcinoma by immunohistochemistry using the new monoclonal anti-CD5 antibody, NCL-CD5-4C7, with a pressure cooker antigen retrieval method. All cases of thymic carcinoma showed positive staining for CD5, predominantly on the cell membrane. Two of 4 cases of atypical thymoma also showed focal positivity, whereas the other types of thymoma were negative. CD5 was detected in cases of malignant tumors other than squamous cell carcinoma and in the normal epithelium of their counterparts. Squamous cell carcinomas of various organs were negative for CD5. Malignant mesothelioma showed peculiar intracytoplasmic staining in contrast to the other tumors. The NCL-CD5-4C7 positivity in thymic epithelial tumors may support the hypothesis suggesting progression of atypical thymoma to thymic carcinoma. NCL-CD5-4C7 may be useful in the differential diagnosis of mediastinal tumors, especially between thymic carcinoma and metastatic squamous cell carcinoma of various primary sites, and for distinguishing malignant mesothelioma from adenocarcinoma of the lung by the different staining pattern.

Histopathologic changes of thymoma preoperatively treated with corticosteroids.

Preoperative treatment of thymoma in advanced stages with corticosteroids may reduce the size of the tumor, but no precise histologic evaluation has been performed. We examined the histopathologic features of pretreatment biopsy and posttreatment surgical specimens of eleven cases of thymoma with such treatment to see the changes of the histologic subtypes based on Muller-Hermelink classification. All specimens were also assessed immunohistochemically for MIB-1 labeling and apoptotic cells to verify the effectiveness of this pretreatment. Seven tumors clinically diminished in size after the treatment with corticosteroids. Fungal infection occurred in three cases postoperatively. The histology of mixed thymomas (two cases) was converted to that of medullary thymoma. Predominantly cortical thymomas (four cases) and cortical thymomas (three cases) changed to show similar histologic features; both became epithelial-rich thymoma with large polygonal tumor cells having indistinct cell borders. In contrast, two well-differentiated thymic carcinomas showed at surgery more prominent squamoid appearance with distinct cell borders. The apoptotic indices of epithelial cells were increased (P = 0.001), and the MIB-1 indices tended to be decreased with corticosteroid treatment. These results suggest that there may be a histogenetic relationship between medullary and mixed thymomas and also between predominantly cortical and cortical thymomas. Corticosteroids may cause degenerative changes in the epithelial cells and lymphocytes and, in thymomas in advanced stages, corticosteroid pretreatment may be warranted, although attention should be paid to infection after surgery.

Membrane attack complex of complement and 20 kDa homologous restriction factor (CD59) in myocardial infarction.

In order to investigate the mechanism of deposition of the complement membrane attack complex (MAC) in cardiomyocytes in areas of human myocardial infarction, the 20 kDA homologous restriction factor of complement (HRF20; CD59) and complement components (Clq. C3d and MAC) were analysed immunohistochemically using specific antibodies. Myocardial tissues obtained at autopsy from nine patients who died of acute myocardial infarction were fixed in acetone and embedded in paraffin. The ages of the infarcts ranged from about 3.5 h to 12 days. In cases of myocardial infarction of 20 h or less, MAC deposition was shown in the infarcted cardiomyocytes without loss of HRF20. Where the duration was 4 days or more, the cardiomyocytes with MAC deposition in the infarcted areas also showed complete loss of HRF20. Outside the infarcts, HRF20 in the cardiomyocytes was well preserved without MAC deposition. The present study suggests that the initial MAC deposition in dead cardiomyocytes can occur as a result of degradation of plasma-membrane by a mechanism independent of complement-mediated injury to the membrane. Loss of HRF20 from dead cardiomyocytes may not be the initial cause of MAC deposition, but may accelerate the deposition process of MAC in later stages of infarction.

PE-35-related antigen expression and CD1a-positive lymphocytes in thymoma subtypes based on Müller-Hermelink classification. An immunohistochemical study using catalyzed signal amplification.

PE-35 monoclonal antibody, detecting a cell-surface antigen of various types of carcinoma and normal epithelium, reacts exclusively with the medullary epithelium in the thymus; therefore, the antigen has been considered as a marker of medullary differentiation in thymomas. Using the catalyzed signal amplification method, which made it possible to apply PE-35 to routinely processed, archival tissues, we examined expression of this antigen, together with CD1a reactivity of lymphocytes, in 40 thymic epithelial tumors subclassified using the Mü1ler-Hermelink system. Medullary thymomas infiltrated with a small number of CD1a-negative lymphocytes were PE-35 positive, although many of the long spindle tumor cells were PE-35 negative. Mixed thymomas and predominantly cortical thymomas, both with prominent CD1a-positive lymphocytes, were also PE-35 positive, although some areas of the latter type were PE-35 negative. Cortical thymomas with decreased numbers of CD1a-positive lymphocytes were largely PE-35 negative. In well-differentiated thymic carcinomas with a few CD1a-positive lymphocytes, two cases were negative, but four cases were at least focally positive with PE-35. All high-grade thymic carcinomas infiltrated with some CD1a-negative lymphocytes were PE-35 positive. These results suggested that medullary thymoma generally possesses the medullary nature, although the latter tends to be lost in the long spindle tumor cells. Mixed and predominantly cortical thymomas may have mixed medullary phenotype and cortical function. Cortical thymoma and many well-differentiated thymic carcinomas may possess the cortical nature, while the large polygonal tumor cells tend to lose immature T-lymphocyte-retaining function.

Proliferative cell nuclear antigen expression in follicular tumours of the thyroid with special reference to oxyphilic cell lesions.

The expression of proliferative cell nuclear antigen (PCNA) in follicular tumours of the thyroid was examined by immunohistochemistry. Both usual nonoxyphilic cell follicular tumours (non-OCT) and oxyphilic cell tumours (OCT) were subdivided into benign, indeterminate, encapsulated carcinoma, and widely invasive carcinoma types. Among non-OCT the percentages of PCNA-positive cells in benign tumours, encapsulated carcinomas, and widely invasive carcinomas was 2.5%-8.6%, 11.8%-39.1%, and 18.6%-20.0%, respectively. There was a statistically significant difference between benign tumours and encapsulated or widely invasive carcinomas, as in previous studies. A value of 10% was appropriate to distinguish benign from malignant lesions. PCNA-positive cells in indeterminate-type non-OCT were not significantly different from those in benign tumours, ranging from 4.3%-19.6%, and occurring at more than 10% in three of six tumours. Among OCT the positivity was less than 10% in benign tumours (4.5%-7.8%) and more than 10% in malignant tumours (14.1%-35.9%) and all the eight indeterminate tumours (12.5%-27.3%), with a statistically significant differences between the benign tumour and each of the latter types. These results indicate that the examination of PCNA is valuable in diagnosis of thyroid follicular tumours and that the use of similar diagnostic criteria may be warranted in both non-OCT and OCT.

Bowenoid papulosis showing polyclonal nature.

Bowenoid papulosis (BP) is characterized clinically by its benign-looking appearance and histologically by the features of high grade squamous intraepithelial lesions (SILs). The external genitalia of young people is a common site of occurrence, and most of the lesions undergo resolution by local treatments or even spontaneously. A strong association between BP and high risk types of human papillomavirus (HPV), especially HPV 16, has been reported and the incorporation of BP into the SIL category is generally accepted, but controversy still exists as to the true nature of BP. We analyzed the clonality of BP lesions occurring on both sides of the vulva of a 15-year-old girl. DNA was subjected to a polymerase chain reaction-based clonal analysis using the highly informative androgen receptor gene (HUMARA) with a nonisotopic modification. The clonal analysis of each BP lesion showed a random X-chromosome inactivation pattern, indicating a polyclonal nature of this disorder. Although monoclonal proliferation of vulvar SIL was recently reported, this is the first report of the polyclonality in a type of SIL diagnosed as BP, supporting a clinicopathologic heterogeneity in SIL of the vulva.