BRAF-mutant mismatch repair deficient invasive colon cancer regressing to sessile serrated lesion.

A 69-year-old female was presented with a history of sigmoid colon cancer, uterine cancer, and intrahepatic carcinomas. After computed tomography revealed a disseminated nodule located in the peritoneum, colonoscopy demonstrated a rather flat-to-slightly elevated lesion with a depressed area located in the ascending colon. The flat component showed color similar to its surrounding area, and the depressed area showed redness and an expanded appearance. We obtained a biopsy specimen from the depressed area, and microscopic examination revealed well-differentiated adenocarcinoma, which was immunohistochemically positive for BRAF V600E-mutated and PMS2 proteins, and showed loss of MSH2 and MSH6 protein expressions. These findings suggested the lesion to have transformed from a sessile serrated lesion (SSL) to mismatch repair (MMR) deficient colon cancer. The patient underwent surgical removal of the nodule, which interpreted as metastasis of intrahepatic cholangiocarcinoma histopathologically. After postoperative chemotherapy, the follow-up colonoscopy revealed only the flat portion of the lesion without depressed area. Consequently, we performed an endoscopic resection, and microscopic examination confirmed the existence of BRAF V600E-mutated protein-positive and MMR protein-retained SSL without residual carcinoma. This is the first report of BRAF-mutant and MMR-deficient colon cancer, in association with SSL, showing regression.

Inverse correlation between age of onset and myocardial amyloid deposition quantified by 99mTc-PYP scintigraphy in patients with wild-type transthyretin amyloid cardiomyopathy.

OBJECTIVE: Wild-type transthyretin amyloidosis cardiomyopathy (ATTRwt-CM) is increasingly recognized as a contributing factor to cardiac insufficiency in the elderly population. We aimed to identify the factors affecting age of onset of ATTRwt-CM, encompassing the assessment of amyloid deposition in myocardial tissue through the use of 99mTc-pyrophosphate (PYP) and clinical parameters. METHODS: A retrospective investigation involving a consecutive cohort of 107 cases, each having been diagnosed with ATTRwt-CM confirmed through histopathological and genetic analysis, was performed. All patients underwent PYP scintigraphy, and the heart-to-contralateral (H/CL) ratio was calculated to measure amyloid deposition in the myocardium. Univariate and multivariate analyses were performed to identify independent predictors of the age of onset of ATTRwt-CM, considering the H/CL ratio and various clinical risk factors for heart failure. RESULTS: Gender (p = 0.03), Creatinine (Cr) (r = 0.32, p < 0.01), hemoglobin (Hb) (r = - 0.44, p < 0.01), albumin (Alb) (r = - 0.32, p < 0.01), brain natriuretic peptide (BNP) (r = 0.21, p = 0.03), low-density lipoprotein-cholesterol (LDL-C) (r = - 0.27, p < 0.01), and H/CL ratio (r = - 0.44, p < 0.01) were all significantly associated with the onset age. In multiple regression analysis, the independent predictive factors for the onset age of ATTRwt-CM were identified as the H/CL ratio (p < 0.01), Hb (p < 0.01), and Cr (p < 0.01). CONCLUSION: The H/CL ratio, Hb, and Cr independently affect age of onset in patients with ATTRwt-CM. The H/CL ratio is inversely correlated with age of onset, and may be the sole factor in the development of heart failure in early onset patients, while it may have a synergistic effect on heart failure with anemia and renal dysfunction in late-onset patients.

Spinal Dissemination of Pineal Parenchymal Tumors of Intermediate Differentiation Over 10 Years After Initial Treatment: A Case Report.

Pineal parenchymal tumors (PPTs) are rare, accounting for less than 0.3% of all primary central nervous system (CNS) tumors. Pineal parenchymal tumors of intermediate differentiation (PPTID) (WHO grade 2 or 3) show an intermediate prognosis between pineocytoma and pineoblastoma. The clinical course is unknown, and the optimal treatment for PPTID, especially for recurrence, has not been determined. We report a case of PPTID with spinal dissemination over 10 years after treatment and survival for four years. A 56-year-old woman presented with headaches and diplopia. Computerized tomography (CT) and magnetic resonance imaging (MRI) revealed a pineal mass, but leptomeningeal dissemination was not identified on whole-spine MRI. Microsurgical gross total tumor resection (GTR) was performed, and the pathological diagnosis was PPTID (grade 3). In addition, a later study found it to harbor a KBTBD4 mutation. She underwent whole-brain radiation therapy with a focal boost. The patient was unable to continue chemotherapy for severe myelosuppression after the first course of treatment. Eleven years after the surgery, she was unable to walk, and a whole-spine MRI revealed multiple masses at C3-4, T4, and cauda equina. Fluorodeoxyglucose-positron emission tomography (FDG-PET) revealed accumulations of the same lesions. No recurrence was observed in the brain. A biopsy of the caudal portion was performed, and the histopathological findings were the same as those of the initial surgery. Spinal dissemination was refractory to chemotherapy but responded to whole spine radiotherapy with focal boost, and she remained tumor-free for four years. We considered good local control with a combination of GTR and subsequent radiation therapy to contribute to long-term survival. The timing of spinal radiation administration is controversial because of the tendency for late cerebrospinal dissemination. The importance of long-term follow-up of the spine and head is emphasized. In PPTID cases with good local control, withholding spinal radiation until spinal dissemination occurs may become a long-term treatment plan.

Age-associated reduction of sinus macrophages in human mesenteric lymph nodes.

There are numerous macrophages and dendritic cells in lymph nodes (LNs). Recent studies have highlighted that sinus macrophages (SMs) in LNs possess antigen-presenting capabilities and are related to anti-cancer immune responses. In this study, we assessed the distribution of SMs in mesenteric LNs removed during surgery for colorectal cancer. A marked reduction of SMs was noted in elderly patients, particularly those over 80 years old. We observed a disappearance of CD169-positive cells in LNs where SMs were reduced. In silico analysis of publicly available single-cell RNA sequencing data from LNs revealed that CD169-positive macrophages express numerous genes associated with antigen presentation and lymphocyte proliferation, similar to dendritic cells' functions. In conclusion, our study demonstrates that SMs, potentially crucial for immune activation, diminish in the LNs of elderly patients. This reduction of SMs may contribute to the immune dysfunction observed in the elderly.

Extranodal NK/T-cell lymphoma with localized relapse in bone marrow of lower leg detected using PET-CT.

Extranodal natural killer (NK)/T-cell lymphoma (ENKTL) is a rare subtype of non-Hodgkin lymphoma (NHL) with poor prognosis, particularly in relapsed or refractory patients. Thus, timely detection of relapse and appropriate disease management are crucial. We present two patients with ENKTL, wherein positron emission tomography-computed tomography (PET-CT) with total-body coverage after induction therapy, detected newly relapsed regions in the bone marrow of the lower leg prior to progression. Case 1: A 47-year-old woman with nasal obstruction, showing 18F-fluoro-deoxyglucose (FDG) uptake in the nasal cavity (Lugano stage IE). After induction therapy (RT-2/3 DeVIC), PET-CT revealed abnormal uptake only in the right fibula. Case 2: A 68-year-old man with a skin nodule/ulcer and an enlarged right inguinal lymph node was diagnosed with advanced ENKTL. A PET-CT scan revealed abnormal uptake in the subcutaneous mass of the right medial thigh, lymph nodes, and descending colon (Lugano stage IV). After induction therapy, PET-CT revealed new abnormal uptake only in the left tibia. In both patients, CT-guided biopsy confirmed ENKTL recurrence. Moreover, PET-CT with whole-body coverage was useful for the timely assessment of relapse and detection of asymptomatic bone involvement. This approach allowed for modifications to treatment strategies in certain patients.

Concordance Between Biopsy and Resection Diagnoses of Uterine Cervical Adenocarcinoma According to the Updated World Health Organization 2020 Classification: A Multi-Institutional Study Elucidating Real-World Practice in Japan.

CONTEXT.­: Endocervical adenocarcinoma is divided into human papillomavirus (HPV)-associated (HPVA) and HPV-independent (HPVI) in the 5h edition of the World Health Organization (WHO) tumor classification launched in 2020. However, the validity of the morphological criteria used for biopsy specimens in real-world practice remains undetermined. OBJECTIVE.­: To validate the utility of the 5th edition of the WHO classification for biopsy samples, focusing on its diagnostic criteria with the aid of ancillary studies. DESIGN.­: We retrieved 217 cases of endocervical adenocarcinoma from 6 institutions, in which glass slides of both biopsy and resection specimens were available for review. Concordance between the biopsy and resection specimen diagnoses was evaluated. For discordant diagnoses, an algorithmic approach with ancillary studies proposed by the international group was applied to confirm their utility to improve the accuracy of biopsy diagnosis. RESULTS.­: The biopsy diagnosis matched the resection specimen diagnosis in 197 cases (concordance rate, 91%; κ = 0.75). The concordance rate was significantly higher for HPVA than HPVI (95% versus 81%, P = .001). There were no significant differences in the proportions of HPVA and HPVI or the accuracy of biopsy diagnosis between the participating institutions. All 19 discordant cases with unstained glass slides available were accurately recategorized as HPVA or HPVI using HPV in situ hybridization; p16 immunohistochemistry was positive in 3 of 9 cases of gastric-type HPVI that were negative by in situ hybridization. CONCLUSIONS.­: The 5th edition of the WHO criteria for biopsy diagnosis of endocervical adenocarcinoma distinguishes HPVA from HPVI well when ancillary studies are adequately applied.

A Rare Case of Adult Poorly Differentiated Chordoma of the Skull Base With Rapid Progression and Systemic Metastasis: A Review of the Literature.

Chordoma is a rare tumor that arises from chordal tissue during fetal life. Recently, the concept of poorly differentiated chordoma, a subtype of chordoma characterized by loss of SMARCB1/INI1 with a poorer prognosis than conventional chordomas, was established. It predominantly occurs in children and is rare in adults. Here, we report a rare adult case of poorly differentiated chordoma of the skull base with a unique course that rapidly systemically metastasized and had the shortest survival time of any adult chordoma reported to date. The patient was a 32-year-old male with a chief complaint of diplopia. MRI showed a widespread neoplastic lesion with the clivus as the main locus. Endoscopic extended transsphenoidal tumor resection was performed. Pathological findings showed that the tumor was malignant, and immunohistochemistry revealed a Ki-67 labeling index of 80%, diffusely positive brachyury, and loss of INI1 expression. The final diagnosis was poorly differentiated chordoma. Postoperatively, the residual tumor in the right cavernous sinus showed rapid growth. The patient was promptly treated with gamma knife three fractions. The residual tumor regressed, but the tumor developed systemic metastasis in a short period, and the patient died seven months after diagnosis. This report of a rapidly progressing and fatal adult poorly differentiated chordoma shows the highest Ki-67 labeling index reported to date. Prompt multidisciplinary treatment should be considered when the Ki-67 labeling index is high.

Long-term outcomes of multidisciplinary treatment combining surgery and stereotactic radiotherapy with Novalis for craniopharyngioma.

Craniopharyngiomas are difficult to resect completely, recurrence is frequent, and hypothalamic/pituitary function may be affected after surgery. Therefore, the ideal treatment for craniopharyngiomas is local control with preservation of hypothalamic and pituitary functions. The purpose of this study is to retrospectively evaluate the long-term efficacy and adverse events of stereotactic radiotherapy (SRT) with Novalis for craniopharyngioma. This study included 23 patients with craniopharyngiomas who underwent surgery between 2006 and 2021 and underwent SRT as their first irradiation after surgery. The median post-irradiation observation period was 88 months, with the overall survival rates of 100 % at 10 years and 85.7 % at 20 years. One patient died of adrenal insufficiency 12 years after irradiation. The local control rate of the cystic component was 91.3 % at 5 years, 83.0 % at 15 years, with no increase in the solid component. No delayed impairment of visual or pituitary function due to irradiation was observed. No new hypothalamic dysfunction was observed after radiation therapy. No delayed adverse events such as brain necrosis, cerebral artery stenosis, cerebral infarction, or secondary brain tumors were also observed. SRT was safe and effective over the long term in patients irradiated in childhood as well as adults, with no local recurrence or adverse events. We believe that surgical planning for craniopharyngioma with stereotactic radiotherapy in mind is effective in maintaining a good prognosis and quality of life.

CXCL10 Expression in Human Colorectal Cancer Tissue and its Correlation With Serum Levels of CXCL10.

BACKGROUND/AIM: CXCL10, a member of the CXC chemokine family, plays a crucial role in immune response by facilitating the chemotaxis of CXCR3-positive immune cells. We examined the expression of CXCL10 to unravel its functional significance in colorectal cancer. MATERIALS AND METHODS: Bioinformatics analysis was performed to investigate CXCL10 expression and its clinicopathological relevance. Subsequently, we examined the correlation between the serum levels of CXCL10 and its expression within cancer tissues. RESULTS: Analysis of the TCGA database revealed that elevated CXCL10 expression in CRC tissues correlates with improved long-term survival and is inversely associated with lymph node infiltration and metastasis. Insights from Gene Ontology and Kyoto Encyclopedia of Genes and Genomes further established a connection between increased CXCL10 and co-regulated gene expression with enhanced immune activation and regulation, mediated by the inhibition of the NOD-like receptor signaling pathway. Single-cell analysis pinpointed myeloid cells and macrophages as the primary sources of CXCL10. Immunohistochemical assessments revealed that a subset of cancer cells and macrophages are positive for CXCL10 expression. CXCL10-positive cells are predominantly located at the invasive front of the tumor. Intriguingly, our findings reveal an inverse correlation between serum CXCL10 levels and its expression in cancer tissues. CONCLUSION: The expression of CXCL10 may play a role in mediating the inflammatory responses at the invasive front in colorectal cancer and is observed to be inversely correlated with serum CXCL10 levels. It is pivotal to elucidate the distinct roles of CXCL10 in colorectal cancer, particularly different functions of cancer-tissue CXCL10 from serum CXCL10.

Waldenstrom's macroglobulinemia-like B cell lymphoma with MYD88 L265P mutation and t(14;18)(q32;q21) involving IGH-MALT1.

A 65-year-old woman was referred to the hospital for further investigation of weight loss, hyperproteinemia, and anemia. Serum immunofixation electrophoresis revealed IgM-κ M protein. Bone marrow examination revealed an increase in the number of B -cells with immunoglobulin kappa light-chain restriction. Although the MYD88 L265P mutation was identified in bone marrow mononuclear cells, which suggested the diagnosis of Waldenstrom's macroglobulinemia (WM), a fusion signal of IgH-MALT1, which is commonly observed in extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) lymphoma, was also identified. Here, we describe a rare case of low-grade B-cell lymphoma with MYD88 L265P mutations accompanying IgH-MALT1.

Expression of macrophage/dendritic cell-related molecules in lymph node sinus macrophages.

The role of sinus macrophages (SMs) in anticancer immune responses has received considerable interest in recent years, but the types of molecules that are expressed in human SMs have not yet been clarified in detail. We therefore sought to identify dendritic cell (DC)- or macrophage-related molecules in SMs in human lymph nodes (LNs). SMs are strongly positive for Iba-1, CD163, CD169, and CD209. CD169 (clone SP216) reacted with almost all SMs, mainly in the cell surface membrane, while CD169 (clone HSn 7D2) reacted with a subpopulation of SMs, mainly in the cytoplasm, with a significant increase observed after IFN-α stimulation. The immunoreactivity of clone HSn 7D2 was markedly reduced after transfection with small interfering RNA against CD169, while that of clone SP216 was slightly reduced. The induction of CCL8 and CXCL10 messenger RNA (mRNA) expression by IFN-α was confirmed using cultured macrophages and RT-qPCR, but fluorescence in situ hybridization did not detect CCL8 and CXCL10 mRNA expression in SMs. Single-cell RNA sequence data of LNs indicated that the highest level of CXCL10 gene expression occurred in monocytes. In conclusion, we found that CD209, also known as DC-related molecule, was expressed in human SMs. The heterogeneity observed in CD169 reacted with cone HSn 7D2 and SP216 was potentially due to the modification of CD169 protein by IFN stimulation. Further, no expression of CXCL10 mRNA in SMs suggested that SMs might be resident macrophages.

Ovarian serous borderline tumors with recurrent or extraovarian lesions: a Japanese, retrospective, multi-institutional, population-based study.

BACKGROUND: Ovarian serous borderline tumors (SBT) are typically unilateral and are primarily treated using hysterectomy and bilateral salpingooophorectomy (SO). However, most young patients prefer fertility-sparing surgeries (FSS) with tumorectomy or unilateral SO. Micropapillary morphology and invasive implants have been designated as histopathological risk indicators for recurrence or metastasis, but their clinical impact remains controversial because of limitations like diagnostic inconsistency and incomplete surgical staging. METHODS: A nationwide multi-institutional population-based retrospective surveillance was conducted with a thorough central pathology review to reveal the clinical features of SBT. Of 313 SBT patients enrolled in the Japanese Society of Clinical Oncology's Surveillance of Gynecologic Rare Tumors, 289 patient records were reviewed for clinical outcomes. The glass slides of patients at stage II-IV or with recurrence or death were re-evaluated by three gynecological pathologists. RESULT: The 10-year overall and progression-free survival (PFS) rates were 98.6% and 92.3%. The median recurrence period was 40 months and 77.0% was observed in the contralateral ovary within 60 months. Patients aged ≤ 35 years underwent FSS more frequently and relapsed more (p < .001). A clinic-pathological analysis revealed diagnosis during pregnancy, FSS, and treatment at non-university institutes as well as advanced stage and large diameter were independent risk factors of recurrence. Among patients having pathologically confirmed SBTs, PFS was not influenced by the presence of micropapillary pattern or invasive implants. CONCLUSION: The recurrence rate was lower in this cohort than previous reports, but the clinical impacts of incomplete resection and misclassification of the tumor were still significant on the treatment of SBT.

Construction of injury process from Japanese consumer product narrative injury data using an ontology-based method.

Understanding of how injuries occur plays an effective role in accident learning and prevention. Existing frameworks focus on crucial information but ignore their causal relationships, which can lead to an incomplete understanding of the injury process. In this study, the descriptive framework of injury data (DFID) is expanded and combined with accident causation models used to elaborate on the causality of each injury factor. Subsequently, the injury process description ontology (IPD-Onto) based on DFID (extension) is established through a seven-step method developed by Stanford University. The IPD-Onto divides injury cases into five unified classes and constructs the injury process through the object properties. The ontology-based description of the injury process (with causal relationships) provides additional description and interpretation capabilities that are understandable by human experts or computers. The results of the Protégé DL query show that the ontology-based method enables the machine to interpret the injury process.

Mismatch repair protein deficiency in endometriosis: Precursor of endometriosis-associated ovarian cancer in women with lynch syndrome.

OBJECTIVE: We aimed to elucidate the pathogenesis of ovarian cancer through the loss of mismatch repair (MMR) proteins in women with Lynch syndrome (LS) in this report. CASE REPORT: Two women with LS underwent surgery for synchronous endometrial cancer and ovarian cancer. In both cases, immunohistochemical examination showed concomitant MMR protein deficiency in endometrial cancer, ovarian cancer, and contiguous ovarian endometriosis. In Case 1, the macroscopically normal ovary included multiple endometrioses with MSH2 and MSH6 expression, and FIGO grade 1 endometrioid carcinoma and contiguous endometriosis without MSH2 and MSH6 expression. In Case 2, all endometriotic cells contiguous with carcinoma in the lumen of the ovarian cyst showed loss of the expression of MSH2 and MSH6. CONCLUSION: Ovarian endometriosis with MMR protein deficiency may progress to endometriosis-associated ovarian cancer in women with LS. Diagnosing endometriosis in women with LS during surveillance is important.

A surgical resection of hepatic granuloma mimicking intrahepatic cholangiocarcinoma: a case report.

Hepatic granuloma is relatively rare, and benign tumor of the liver. Herein, we report an unusual case of hepatic granuloma mimicking intrahepatic cholangiocarcinoma (ICC). An 82-year-old woman with a history of viral hepatitis B was admitted for investigation of liver mass in the left lobe. Dynamic computed tomography revealed a mostly hypo-enhancing main tumor with a peripheral ring enhancement, and positron emission tomography demonstrated localized an abnormal accumulation of fludeoxyglucose. Considering the possibility of malignant disease, extended left hepatectomy was performed. The resected tumor was macroscopically a periductal infiltrating nodular type, 4.5 × 3.6 cm in diameter. The pathological findings showed that granuloma and coagulative necrosis were present, and diagnosis of hepatic granuloma was confirmed. Pathological studies demonstrated that periodic acid-Schiff stain, Grocott-Gomori stain and Ziehl-Neelsen stain were all negative in the lesion.

Two children with lymphocytic hypophysitis presenting with positive anti-rabphilin-3A antibody.

Lymphocytic hypophysitis (LYH) is a rare chronic inflammatory disease characterized by lymphocytic infiltration of the anterior or posterior pituitary gland and hypothalamus. LYH is subdivided into lymphocytic adenohypophysitis (LAH), lymphocytic infundibulo-neurohypophysitis (LINH), and lymphocytic panhypophysitis (LPH) depending on the primary site. Most cases occur in adults, with few cases reported in children, and it is especially important to distinguish LYH from suprasellar malignancies, such as germ cell tumors and other neoplastic diseases. Although a biopsy is necessary for definitive diagnosis, it is desirable to be able to diagnose the disease without biopsy if possible, especially in children, because of the surgical invasiveness of the procedure. Recently, serum anti-rabphilin-3A antibodies have attracted attention as diagnostic markers for LYH, especially in LINH, but there are only a few reports on pediatric patients. In the present study, we experienced two children with LPH and LAH, respectively, who tested positive for anti-rabphilin-3A antibodies. This is the first report of children with LYH other than LINH positive for anti-rabphilin-3A antibodies, and anti-rabphilin-3A antibodies may be a useful non-invasive diagnostic marker not only for LINH but also for LYH in general. We also discuss the sensitivity and specificity of anti-rabphilin-3A antibody testing in cases where histological diagnosis has been made.

Lynch syndrome-associated chordoma with high tumor mutational burden and significant response to immune checkpoint inhibitors.

Chordoma is a rare malignant bone tumor arising from notochordal tissue. Conventional treatments, such as radical resection and high-dose irradiation, frequently fail to control the tumor, resulting in recurrence and re-growth. In this study, genetic analysis of the tumor in a 72-year-old male patient with refractory conventional chordoma of the skull base revealed a high tumor mutational burden (TMB) and mutations in the MSH6 and MLH1 genes, which are found in Lynch syndrome. The patient and his family had a dense cancer history, and subsequent germline genetic testing revealed Lynch syndrome. This is the first report of a chordoma that has been genetically proven to be Lynch syndrome. Chordomas usually have low TMB; however, this is an unusual case, because the TMB was high, and immune checkpoint inhibitors effectively controlled the tumor. This case provides a basis for determining the indications for immunotherapy of chordoma based on the genetic analysis. Therefore, further extensive genetic analysis in the future will help to stratify the treatment of chordoma.

Poor Treatment Outcomes of Locally Advanced Cervical Adenocarcinoma of Human Papilloma Virus Independent Type, Represented by Gastric Type Adenocarcinoma: A Multi-Center Retrospective Study (Sankai Gynecology Study Group).

The revised World Health Organization classification of cervical cancer divides adenocarcinomas into human papillomavirus-associated (HPVa) and -independent (HPVi) types; the HPVi type is represented by the gastric type. The treatment outcomes of locally advanced adenocarcinoma (LaAC), based on this classification, are understudied. We investigated the outcomes of patients with HPVa and HPVi LaACs. Data for all consecutive patients with stage IB3 to IIIC1 adenocarcinoma who received treatment at 12 institutions throughout Japan between 2004 and 2009 were retrieved to analyze progression-free and overall survival. Central pathological review classified 103 and 48 patients as having HPVa and HPVi tumors, respectively. Usual- (84%) and gastric- (90%) type adenocarcinomas were the most frequent subtypes. Surgery was the primary treatment strategy for most patients. Progression-free and overall survival of patients with HPVi were worse than those of patients with HPVa (p = 0.009 and 0.032, respectively). Subgroup analysis by stage showed that progression-free survival was significantly different for stage IIB. The current surgical treatment strategy for LaACs is less effective for HPVi tumors than for HPVa tumors, especially those in stage IIB.

An epileptogenic intracranial cystic lesion lined with fallopian tube-type epithelium: illustrative case.

BACKGROUND: Intracranial cystic lesions are often a trigger for epileptic seizures. However, there has never been a report of a cystic lesion lined with fallopian tube-type epithelium. OBSERVATIONS: A 48-year-old female presented with a cystic lesion in the right occipital lobe, which gradually grew over 8 years. Right occipital lobe epilepsy was diagnosed based on visual aura, convulsive seizures, and electroencephalogram findings and the cyst was surgically removed. Further examination revealed the cyst was lined with ciliated cells, which had morphological and immunohistochemical features similar to those of fallopian tube epithelium. LESSONS: The characteristics of the cyst did not conform to any known types of benign cystic lesion. To the authors' knowledge, no such cyst has been reported before. The authors discuss the origins and pathogenesis of this unfamiliar cystic lesion.