Sweat-gland carcinoma with neuroendocrine differentiation (SCAND): a clinicopathologic study of 13 cases with genetic analysis.

Low-grade neuroendocrine carcinoma of the skin (LGNECS) was proposed in 2017 as a new primary cutaneous neoplasm with neuroendocrine differentiation; however, it is not yet well known due to its rarity. Herein, we perform a detailed clinicopathologic analysis of 13 cases as well as panel DNA sequencing in three cases. The study included 12 males and 1 female with a median age of 71 (43-85) years. All lesions occurred on the ventral trunk. The mean tumor size was 2.2 (0.8-11.0) cm. The histopathology resembled that of well-differentiated neuroendocrine tumors (NETs) in other organs, but intraepidermal pagetoid spreading was seen in 8 (61.5%) cases and stromal mucin deposits in 4 (30.8%). Immunoreactivity for CK7, CK19, EMA, BerEP4, CEA, chromogranin A, synaptophysin, INSM1, GCDFP15, GATA3, ER, and bcl-2 were present in varying degrees in all tested cases. PTEN c.165-1G>A splice site mutation was detected by panel sequencing in one case, and GATA3 P409fs*99 and SETD2 R1708fs*4 in another case. Lymph node metastasis was seen significantly in cases with tumor size >2.0 cm [8/8 (100%) vs. 1/5 (20%)]. All three cases with size >3.0 cm were in unresectable advanced-stage [3/3 (100%) vs. 1/10 (10%)], and two of the three patients succumbed to the disease. The two cases of death revealed mild nuclear atypia (mitosis: 1/10 HPFs) and moderate nuclear atypia (2/10 HPFs). Thus, tumor size would be a better prognostic factor than nuclear atypia, mitotic count, and Ki67 index, unlike in NETs. These clinicopathologic and immunohistochemical features would represent the characteristics as skin adnexal tumors with apocrine/eccrine differentiation rather than NETs; therefore, we rename it as sweat-gland carcinoma with neuroendocrine differentiation (SCAND).

Neutrophil-to-lymphocyte ratio is associated with survival and sentinel lymph node positivity in invasive cutaneous squamous cell carcinoma: A retrospective study.

BACKGROUND: The neutrophil-to-lymphocyte ratio (NLR) is a known prognostic biomarker for survival and is predictive of sentinel lymph node (SLN) positivity in some cancers. However, its usefulness as a prognostic biomarker for cutaneous squamous cell carcinoma (cSCC) has not been fully investigated. OBJECTIVE: Our objective was to investigate the relationship between the NLR and the disease-specific survival and SLN positivity in patients with cSCC. METHODS: In this single-center retrospective case series, we analyzed patients with cSCC who underwent blood tests prior to the initiation of treatment at our oncology hospital. The relationship between the patients' clinical characteristics (including the NLR) and the disease-specific survival and SLN positivity was evaluated using univariate and multivariate analyses. RESULTS: An elevated NLR was an independent prognostic factor for poor disease-specific survival and a predictive factor for SLN positivity. LIMITATIONS: Limitations include the small number of participants and selection bias due to the large proportion of high-risk cases in our patient population. CONCLUSION: NLR is a useful biomarker in cSCC because it is simple to measure and can predict prognosis.

Long-term follow up of nivolumab in previously untreated Japanese patients with advanced or recurrent malignant melanoma.

The immune checkpoint inhibitor nivolumab inhibits the programmed death 1 receptor and suppresses the immune resistance of cancer cells. This is a long-term follow up of a single-arm, open-label, multicenter, phase II study of nivolumab in untreated Japanese patients with stage III/IV or recurrent melanoma. In addition, a post-hoc subgroup analysis stratified by melanoma types was performed. Nivolumab was administered intravenously at a dose of 3 mg/kg every 2 weeks. The primary endpoint was the overall response rate (ORR), and secondary endpoints included overall survival (OS), progression-free survival (PFS), best overall response, the disease control rate and change in tumor diameter. Safety was assessed by recording treatment-related adverse events (TRAE), including select immune-related adverse events. Of the 24 patients initially included in the primary phase II study, 10 survived for over 3 years (41.7%). The ORR was 34.8% (90% confidence interval [CI]: 20.8, 51.9) for all patients. When analyzing by melanoma type, the ORR was 66.7% (90% CI: 34.7, 88.3) for superficial spreading, 33.3% (90% CI: 11.7, 65.3) for mucosal, and 28.6% (90% CI: 10.0, 59.1) for acral lentiginous tumors. The median OS was 32.9 months, the 3-year OS rate was 43.5%, and the 3-year PFS rate was 17.2%. A long-term response was observed in all the tumor types. The most common TRAE included skin toxicity (45.8%) and endocrine disorders (29.2%). This study demonstrated the long-term efficacy and tolerability of nivolumab in patients with advanced or recurrent melanoma, irrespective of melanoma type.

Efficacy and safety of nivolumab in Japanese patients with previously untreated advanced melanoma: A phase II study.

Treating advanced or recurrent melanoma remains a challenge. Cancer cells can evade the immune system by blocking T-cell activation through overexpression of the inhibitory receptor programmed death 1 (PD-1) ligands. The PD-1 inhibitor nivolumab blocks the inhibitory signal in T cells, thus overcoming the immune resistance of cancer cells. Nivolumab has shown promising anticancer activity in various cancers. We carried out a single-arm, open-label, multicenter, phase II study to investigate the efficacy and safety of nivolumab in previously untreated Japanese patients with advanced melanoma. Twenty-four patients with stage III/IV or recurrent melanoma were enrolled and received i.v. nivolumab 3 mg/kg every 2 weeks until disease progression or unacceptable toxicity. The primary endpoint was overall response rate evaluated by an independent radiology review committee. The independent radiology review committee-assessed overall response rate was 34.8% (90% confidence interval, 20.8-51.9), and the overall survival rate at 18 months was 56.5% (90% confidence interval, 38.0-71.4). Treatment-related adverse events (AEs) of grade 3 or 4 only occurred in three patients (12.5%). Two patients discontinued nivolumab because of AEs, but all AEs were considered manageable by early diagnosis and appropriate treatment. Subgroup analyses showed that nivolumab was clinically beneficial and tolerable regardless of BRAF genotype, and that patients with treatment-related select AEs and with vitiligo showed tendency for better survival. In conclusion, nivolumab showed favorable efficacy and safety profiles in Japanese patients with advanced or recurrent melanoma, with or without BRAF mutations. (Trial registration no. JapicCTI-142533.).

Cytokine biomarkers to predict antitumor responses to nivolumab suggested in a phase 2 study for advanced melanoma.

Promising antitumor activities of nivolumab, a fully humanized IgG4 inhibitor antibody against the programmed death-1 protein, were suggested in previous phase 1 studies. The present phase 2, single-arm study (JAPIC-CTI #111681) evaluated the antitumor activities of nivolumab and explored its predictive correlates in advanced melanoma patients at 11 sites in Japan. Intravenous nivolumab 2 mg/kg was given repeatedly at 3-week intervals to 35 of 37 patients enrolled from December 2011 to May 2012 until they experienced unacceptable toxicity, disease progression, or complete response. Primary endpoint was objective response rate. Serum levels of immune modulators were assessed at multiple time points. As of 21 October 2014, median response duration, median progression-free survival, and median overall survival were 463 days, 169 days, and 18.0 months, respectively. The overall response rate and 1- and 2-year survival rates were 28.6%, 54.3%, and 42.9%, respectively. Thirteen patients remained alive at the end of the observation period and no deaths were drug related. Grade 3-4 drug-related adverse events were observed in 31.4% of patients. Pretreatment serum interferon-γ, and interleukin-6 and -10 levels were significantly higher in the patients with objective tumor responses than in those with tumor progression. In conclusion, giving repeated i.v. nivolumab had potent and durable antitumor effects and a manageable safety profile in advanced melanoma patients, strongly suggesting the usefulness of nivolumab for advanced melanoma and the usefulness of pretreatment serum cytokine profiles as correlates for predicting treatment efficacy.

Intratumoral injection of IFN-ß induces chemokine production in melanoma and augments the therapeutic efficacy of anti-PD-L1 mAb.

Despite recent advances in treatment for melanoma patients through using immune checkpoint inhibitors, these monotherapies have limitations and additional treatments have been explored. Type I IFNs have been used to treat melanoma and possess immunomodulatory effects including enhancement of T-cell infiltration. T-cell plays a critical role in immune checkpoint therapies via restoration of effector functions and tumor infiltration by T-cells predicts longer survival in a variety of cancer types. Moreover, tumor-infiltrating T-cells are associated with the expression of chemokines such as CCL5 and CXCR3 ligands in tumor tissues. We therefore investigated whether intratumoral injection of IFN-ß induces the expression of CCL5 and CXCR3 ligands in melanoma cells and has additional antitumor effects when combined with anti-PD-L1 mAb treatment. IFN-ß treatment enhanced CD8+ T-cell infiltration into tumors and CCL5 and CXCR3 ligand expression. In vivo studies using a mouse model showed that monotherapy with IFN-ß, but not with anti-PD-L1 mAb, inhibited tumor growth in comparison to control. However, the therapeutic efficacy of IFN-ß was significantly enhanced by the addition of anti-PD-L1 mAb. This antitumor response of combination therapy was abrogated by anti-CD8 mAb and IFN-ß augmented the neoantigen-specific T-cell response of anti-PD-L1 mAb. Our findings suggest that IFN-ß induces the expression of CCL5 and CXCR3 ligands in melanoma, which could play a role in T-cell recruitment, and enhances the efficacy of anti-PD-L1 mAb treatment in a CD8-dependent manner.

Frequency of level II and III axillary nodes metastases in patients with positive sentinel lymph nodes in melanoma: a multi-institutional study in Japan.

BACKGROUND: Axillary lymph node dissection (ALND) has been recommended to include levels I-III for melanoma patients who have evidence of metastasis in the axillary sentinel lymph node (SLN). The extent of the subsequent axillary dissection is in debate. The objective of this study was to determine the frequency of metastasis of level III nodes in addition to that of level II nodes in this setting. METHODS: A multi-institutional retrospective study was undertaken in 14 melanoma treatment centers in Japan. RESULTS: Between 2007 and 2012, 69 patients with involved axillary SLNs underwent a subsequent ALND and 55 underwent level I and II dissections. Level III metastatic nodes, which is our primary endpoint, were seen in only 1 patient (1.5 %). The level II metastatic rate was 4.4 %. CONCLUSIONS: Our study sample size was small, but melanoma patients with positive SLN rarely had level III disease, suggesting that level III dissection may be unnecessary. We also found that level II metastasis was not so frequent. More evidence is needed to standardize the extent of ALND and to identify the patients who would have the most benefit with undergoing level II dissection for positive axillary SLNs.

Japanese Dermatological Association guidelines: Outlines of Japanese clinical guidelines for basal cell carcinoma 2021.

To summarize the current therapies for skin cancers, the Japanese Skin Cancer Society issued the first guidelines for skin cancers, including melanoma, squamous cell carcinoma, basal cell carcinoma (BCC), and extramammary Paget's disease, in 2007. These guidelines were revised in 2015. Herein, we present the English version of the 2021 edition of the Japanese clinical guidelines for BCC. In the latest edition, all procedures were performed according to the Grading of Recommendations, Assessment, Development and Evaluation systems. The clinical questions that could not be answered were selected for further analysis. A comprehensive literature search, systematic review, and recommendations for each clinical question were determined by a multidisciplinary expert panel comprising dermatologists, a plastic and reconstructive surgeon, and a pathologist. Surgical resection is the gold-standard therapy of BCC. Radiotherapy or topical treatments, other than surgical resection, have been used in some cases. Patients with unresectable or metastatic BCC require systemic therapy. Novel agents, such as immune response modifiers or hedgehog pathway inhibitors, are emerging worldwide for the treatment of BCC. Based on these viewpoints, four relevant clinical questions regarding, surgical resection, radiotherapy, topical treatment, and systemic therapy, were raised in this report that aims to help clinicians select suitable therapies for their patients.

Sentinel lymph node biopsy in extramammary Paget disease: A 13-year institutional experience.

Whether sentinel lymph node biopsy status is a prognostic factor or effective in determining treatment strategies in extramammary Paget disease remains unclear. This study aimed to investigate the significance of sentinel lymph node biopsy in extramammary Paget disease. We retrospectively reviewed the clinical information of previously untreated patients with invasive extramammary Paget disease who underwent wide local excision of the primary tumor and sentinel lymph node biopsy at our hospital between April 2008 and March 2021. Clinical data including the baseline neutrophil-to-lymphocyte ratio and recurrence-free survival were analyzed. Sentinel lymph node metastases were classified as macrometastases and micrometastases, with a cut-off value for sentinel lymph node tumor burden of 2 mm. Univariate and multivariate analyses of factors affecting sentinel lymph node biopsy positivity and recurrence-free survival rates were performed. Overall, 85 patients were included in the analysis. Patients in the sentinel lymph node biopsy-positive group (n = 26) had a significantly higher invasion level and neutrophil-to-lymphocyte ratio. According to multivariate analyses, invasion level and a high neutrophil-to-lymphocyte ratio were independent predictive factors for sentinel lymph node biopsy positivity, and the sentinel lymph node biopsy status was an independent prognostic factor for recurrence-free survival. In conclusion, sentinel lymph node biopsy provides an accurate risk classification and clinical indication for postoperative follow-up in patients with invasive extramammary Paget disease.

Prognostic indicators in 35 patients with extramammary Paget's disease.

BACKGROUND: Extramammary Paget's disease (EMPD) is an uncommon skin tumor that usually occurs in the genital area. Few studies on EMPD have been conducted. OBJECTIVE: To evaluate the clinical and pathologic features, treatments, recurrence, survival rates, and prognostic factors of EMPD. METHODS: A total of 35 (27 men and 8 women) patients with EMPD was analyzed. The average age of the patients was 73.4 years. RESULT: Twenty nine Of the 35 patients had lesions in the genital area, one in the genital and perianal area, three in the axillary area and two in the perianal area. Eighteen patients had in situ lesions, five had inguinal lymph node metastases and two had distant metastases at the time of diagnosis. Surgical resection was performed in 30 cases and radiation therapy, was administered in three cases. Six patients died of EMPD, and the overall 5 year survival rate was 75%. CONCLUSION: The presence of a nodule on the primary lesion, clinically palpable lymph nodes, the level of tumor invasion, and lymph node metastases were found to be significant prognostic factors in the 35 EMPD cases at our institution.

Neutrophil-to-lymphocyte ratio is a potential prognostic biomarker for extramammary Paget disease: A retrospective study.

The neutrophil-to-lymphocyte ratio (NLR) is a useful prognostic biomarker for many cancer types. However, the prognostic value of NLR in patients with extramammary Paget disease (EMPD) remains unclear. This study aimed to determine whether NLR is associated with overall survival (OS) in patients with EMPD. In this single-center retrospective case series, we analyzed data of 109 patients with previously untreated EMPD who presented to our hospital. Data on age, sex, primary tumor site, invasion level, presence of lymph node and distant metastases, baseline NLR, and OS were analyzed. The enrolled patients were classified into the metastatic or non-metastatic EMPD groups. The metastatic EMPD group had higher invasion level and NLR value (p < 0.001 and p = 0.005, respectively) compared with the non-metastatic EMPD group. Cox proportional hazards model analysis showed invasion level (p = 0.0093) and NLR value (p = 0.019) to be independent prognostic factors for OS. Notably, multivariate analysis revealed that invasion level (p = 0.045) and NLR value (p = 0.036) were independent prognostic factors for OS in the metastatic EMPD group. The limitations of this study include the small number of participants and its retrospective nature. In conclusion, since NLR can be routinely assessed with high feasibility, it might be a useful biomarker for predicting prognosis in patients with EMPD.

Concordance in judgment of clinical borders of basal cell carcinomas in Japanese patients: A preliminary study of JCOG2005 (J-BASE-MARGIN).

Basal cell carcinoma is the most common type of skin cancer, and surgical excision with clear margins is the standard of care. Surgical margins are determined based on risk factors (high or low risk) for recurrence according to the National Comprehensive Cancer Network and Japanese basal cell carcinoma guidelines. The clarity of the clinical tumor border (well-defined or poorly defined) is considered a risk factor, and significant discrepancies in the judgment of clinical tumor borders among dermato-oncologists may occur. Therefore, we analyzed the dermato-oncologists' concordance in judging the clinical tumor border of basal cell carcinoma. Forty-seven dermato-oncologists (experts: 37; young trainees: 10) participated in this study. The datasets of clinical and dermoscopic photographs of 79 Japanese cases of head and neck basal cell carcinoma were used to determine the concordance in the judgment of clinical tumor border. The probability of the border that was selected more often was used to calculate the rater agreement rate for each dataset. Correct judgment was defined as a more frequently selected border, and the concordance rate of clarity of clinical tumor border for each dermato-oncologist was calculated based on the definition of the correct judgment. A median concordance rate of 85% or higher for all dermato-oncologists was predefined as an acceptable rate for clinical use. Of the 79 datasets, rater agreement rates were 80-100%, 60-79%, and 51-59% for 55, 19, and five datasets, respectively. The median concordance rate for all dermato-oncologists was 86% (interquartile range: 82-89%). There was no significant difference in the concordance rate between the experts and the trainees (median, 87% vs. 85.5%; p = 0.58). The concordance rates of dermato-oncologists for all datasets were relatively high and acceptable for clinical use.

Five-year survival with nivolumab in previously untreated Japanese patients with advanced or recurrent malignant melanoma.

We report the 5-year follow-up results from a single-arm, open-label, multicenter phase II study (ONO-4538-08) conducted in Japan. Twenty-four patients with treatment-naïve, recurrent, or unresectable stage III/IV malignant melanoma received 3 mg/kg nivolumab every 2 weeks until progressive disease or unacceptable toxicity occurred. The 5-year overall survival (OS) rate was 26.1%. Five years after the start of nivolumab treatment, there were six survivors. The 5-year OS rate was 66.7% for patients with a superficial spreading type, 14.3% for acral lentiginous type, and 16.7% for mucosal type. The 5-year progression-free survival rate was 17.2%. No new cases of partial response or complete response were observed after 3 years, and overall response and disease control rates were similar to those reported at 3 years. The treatment-related adverse events reported between the 3- and 5-year follow-up periods were anemia (grade 2), white blood cell count decrease (grade 2), and psoriasiform dermatitis (grade 2) in one patient each. No new grade 3 or higher treatment-related adverse events occurred in this period. In conclusion, first-line treatment with nivolumab in Japanese patients with unresectable or metastatic melanoma resulted in confirmed long-term survival. No new safety signals were reported in the studied population.

Outcome of combination therapy using BRAF and MEK inhibitors among Asian patients with advanced melanoma: An analysis of 112 cases.

BACKGROUND: As most clinical trials evaluating BRAF and MEK inhibitor combination therapy (B + Minh) have been conducted in Western countries, little is known about the effect of B + Minh among East Asian populations. MATERIAL AND METHODS: Data from patients with advanced melanoma treated using B + Minh (either dabrafenib + trametinib or encorafenib + binimetinib) were retrospectively collected from 16 institutes in Japan. Response rates, adverse events, patterns of failure and survival were analysed. RESULTS: We analysed 112 of 144 collected patient records and, of these, 14 had acral/mucosal melanoma. The response rate for the entire cohort was 75.0%. There were no statistical differences in response rates between acral/mucosal and cutaneous melanomas (64.3% versus 76.5%), whereas previous treatment using immune checkpoint inhibitors (ICIs) did not affect response (72.7% versus 73.9%) to B + Minh, response to ICI after B + Minh was only 20%. Patients who achieved complete response had the best overall survival rates at 24 months (94.7%). Elevated serum lactate dehydrogenase levels and 3 or more metastatic sites were independently associated with survival. The most common relapse site was the brain (17.9%). More than half of the patients (58.8%) experienced grade III/IV pyrexia. CONCLUSION: B + Minh was effective among Japanese patients with melanoma, including those with acral/mucosal melanoma. Factors associated with survival were similar to previous Western studies. B + Minh response was not affected by the previous use of ICI; however, vigilance against brain metastasis during B + Minh therapy is required as the brain was our most commonly encountered relapse site.

Vitiligo expansion and extent correlate with durable response in anti-programmed death 1 antibody treatment for advanced melanoma: A multi-institutional retrospective study.

Vitiligo is an autoimmune disorder resulting from the destruction of melanocytes. Several reports indicate the association between vitiligo and treatment response in advanced melanoma during immunotherapy. It has not been investigated, however, if an increase of vitiligo while on treatment with anti-programmed death 1 (PD-1) antibodies is associated with more durable responses. The aim of this study is to evaluate the correlation between the vitiligo dynamics and clinical efficacy of anti-PD-1 antibodies. This study included advanced melanoma patients who were treated with nivolumab or pembrolizumab and developed vitiligo thereafter. Correlation between vitiligo expansion (defined as an increase of lesion size at two separate time points at least 4 weeks apart) as well as vitiligo extent (body surface area [BSA] affected) and clinical efficacy based on response rate, progression-free survival and overall survival was assessed. We retrospectively reviewed 29 patients. The median time from the initiation of anti-PD-1 antibody to vitiligo onset was 4.3 months in patients who showed a response and 5.5 months in patients who showed no response (P = 0.31). Twelve patients showed vitiligo expansion, and in nine of these patients, vitiligo increased to grade 2 (covering ≥ 10% BSA). Vitiligo expansion and grade 2 vitiligo showed no improvement in treatment response (P = 0.59 and 0.25) but were associated with prolonged progression-free survival (P = 0.019 and 0.04). Grade 2 vitiligo also showed a trend for prolonged overall survival (P = 0.07). Trend of expansion and larger vitiligo extent may be predictive factors of prolonged survival during anti-PD-1 antibody in melanoma patients.

Continued Chemotherapy After Concurrent Chemoradiotherapy Improves Treatment Outcomes for Unresectable Cutaneous Squamous Cell Carcinoma: An Analysis of 13 Cases.

Background: There is no standard systemic therapy for unresectable cutaneous squamous cell carcinoma (ucSCC), although various chemotherapy regimens have been reported. In our department, concurrent chemoradiotherapy (CCRT) for ucSCC resulted in a 1-year survival rate similar to that of resectable cutaneous squamous cell carcinoma (cSCC). Treatment involves continued chemotherapy after CCRT. Here, we report the importance of continued chemotherapy after CCRT, based on treatment outcomes. Patients and Methods: We retrospectively evaluated 13 patients with ucSCC, assessing the overall survival, overall response rate (ORR), and disease control rate (DCR). Results: CCRT with continued chemotherapy resulted in an ORR of 84.6%, DCR of 92.3%, and 1-year survival rate of 75%. Of the 13 patients treated with CCRT with continued chemotherapy, 6 had no metastasis. The remaining 7 patients developed metastasis to other organs or lymph nodes beyond the regional lymph nodes, although most sites of metastasis were outside the irradiation area. Conclusion: We conclude that CCRT with continued chemotherapy was effective in treating the irradiation site (primary lesion and regional lymph nodes) and any organ metastasis, although, it is unclear for how long the treatment remains effective.

Dynamics of neutrophil and C-reactive protein reflect the clinical course of pyrexia during combination therapy with dabrafenib and trametinib.

Pyrexia is the most common adverse event in patients with melanoma or other solid organ malignancies that are treated with the combination of dabrafenib and trametinib (combi-DT). Given the expanded indication for combi-DT, management of pyrexia is a high priority. No previous case series has revealed which blood markers reflect the course of pyrexia and there is no consensus on the management strategy for pyrexia. The current case series study describes the utility of neutrophil count (NC), neutrophil ratio (NR) and C-reactive protein (CRP) in 11 patients with metastatic melanoma and BRAF V600 mutations who experienced pyrexia during combi-DT in our department. We also described the clinical course of pyrexia episodes that were managed with the concomitant use of oral prednisolone and immediate withdrawal of combi-DT. Consequently, the analysis of 37 pyrexia episodes in 11 patients showed that the differences in NC, NR and CRP at the onset of pyrexia were significantly different from those at pyretolysis (P = 0.01, 0.006 and 0.03, respectively). Additionally, in the 24 pyrexia episodes treated with the concomitant use of oral prednisolone and the immediate withdrawal of combi-DT, the mean duration of pyrexia and the mean time to restart combi-DT were 3 and 6 days, respectively. Therefore, the blood markers that reflect the course of pyrexia during combi-DT may be helpful for the appropriate management of pyrexia; also, our management strategy for pyrexia successfully reduced the duration of pyrexia and did not require a long-term drug holiday. Further large-scale studies are required to verify our results.

The expression of cell adhesion molecule 1 and its splicing variants in Sézary cells and cell lines from cutaneous T-cell lymphoma.

Cell adhesion molecule 1 (CADM1) is aberrantly expressed by T-cell neoplasms such as adult T-cell leukemia/lymphoma (ATLL) and mycosis fungoides (MF). We studied the expression of CADM1 and its splicing variants in Sézary syndrome (SS), MF, other cutaneous T-cell lymphoma (CTCL), and cell lines derived from T- and B-cell lymphomas. Soluble CADM1 was measured in the patients' sera. CADM1+ cells in the blood and skin lesions were examined by flow cytometry and immunostaining, respectively. Soluble CADM1 was measured by ELISA, and the splicing variants of CADM1 transcripts were determined by reverse transcriptase-polymerase chain reaction, followed by sequencing. As a result, circulating CADM1+ cells were significantly increased in seven out of 10 patients with SS, ranging from 7.9% to 74.5% of the CD3+CD4+ fractions (median 33.7%; cut-off value 6.5%). The percentages of CADM1+ cells were usually less than those of circulating Sézary cells. CADM1 was expressed, to various degrees, in six of nine T-cell lines derived from SS, MF, ATLL, and anaplastic large cell lymphoma (ALCL), but negative in B-cell lymphoma-derived cell lines. CADM1+ cells were present in the skin infiltrates of MF, SS, ATLL and ALCL. Serum levels of soluble CADM1 were not significantly elevated in SS/MF. Three major splicing variants of CADM1 expressed by neoplastic T-cells contained different combinations of the exons 7, 8, 9 and 11, including a putative oncogenic variant composed of exons 7-8-9-11. In conclusion, CADM1 is frequently expressed in Sézary cells and cell lines from CTCL.