BACKGROUND: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and clinically aggressive hematologic malignancy originating from the precursors of plasmacytoid dendritic cells. BPDCN often involves the skin, lymph nodes, and bone marrow, with rapid clinical progression and a poor prognosis. The BPDCN diagnosis is mainly based on the immunophenotype.
METHODS: In this paper, we retrospectively analyzed 2 cases of BPDCN. Both patients were elderly males. The lesions manifested as skin masses. Morphological manifestations included diffuse and dense tumor cell infiltration of the dermis and subcutaneous tissues. Immunohistochemistry staining showed that cluster of differentiation CD4, CD56, CD43, and CD123 were positive.
CONCLUSIONS: In this paper, we retrospectively analyzed 2 cases of BPDCN. Both patients were elderly males. The lesions manifested as skin masses. Morphological manifestations included diffuse and dense tumor cell infiltration of the dermis and subcutaneous tissues. Immunohistochemistry staining showed that cluster of differentiation CD4, CD56, CD43, and CD123 were positive.

Sickle cell disease (SCD) is an autosomal recessive genetic disorder characterized by the abnormal formation of sickle hemoglobin (HbS). Under conditions of deoxygenation, HbS undergoes polymerization, resulting in microvascular occlusion, tissue hypoxia, and infarction. The elevated mortality rate associated with SCD is primarily attributed to complications such as sepsis, acute chest syndrome, stroke, acute multiorgan failure, and pulmonary hypertension. Despite advancements in awareness and treatments, preventing mortality in young individuals with SCD remains a formidable challenge. In an effort to shed light on these challenges, we present a case of unexpected death associated with SCD to emphasize the pressing need for continued research and intervention strategies to improve patient outcomes.

Papillary fibroelastoma (PFE) is a benign tumor that arises mostly from left-sided valves. PFE can cause stroke, and surgical resection may be needed. Lambl\'s excrescence (LE) is a filiform valvular lesion and is considered a possible cause of stroke. A 79-year-old man with light-headedness and left-sided hemiparesis was diagnosed with stroke. Transesophageal echocardiography (TEE) revealed a round-shaped mobile mass in the left ventricular outflow tract (LVOT), which was considered the cause of the stroke. Surgical resection was performed transaortically, and during surgery, a mass was incidentally detected on the noncoronary cusp (NCC), which was also resected followed by aortic valve replacement. Pathology confirmed that the mass in the LVOT was a PFE and that the filiform mass on the NCC was LE. We herein report a rare case of PFE in the LVOT and coexisting LE on the NCC. A careful examination via TEE helps to identify other possible causes of stroke hidden behind the obvious cause.

Heterotopic brain tissue is rare and has not been reported. Our center made the first report. 4 years and 2 months old Girl presented with a cystic mass in the right adrenal gland 2 weeks after right upper abdominal pain. The operation was successful, and the diagnosis was confirmed by postoperative pathology. 6 months after the procedure, the incision healed well without recurrence. This case report has a detailed diagnosis and treatment process and satisfactory examination results. It can provide a reference for diagnosing and treating clinical HBT and reduce the risk of misdiagnosis and mistreatment.

Background: Malignant mesothelioma (MM) is a tumor originating from the pleura, peritoneum, or pericardial cavity. It is divided into diffuse and localized malignant mesothelioma, with four subtypes in diffuse MM: epithelioid, sarcomatoid, desmoplastic, and biphasic, with biphasic being less common. The onset of this tumor is insidious, and the prognosis is extremely poor in some cases, with a median survival of 6-18 months and no standard treatment options in the past. Aims: We report a case of peritoneal malignant mesothelioma that was successfully treated with transformative therapy. We also review the literature in the hope of providing reference for the treatment and pathological diagnosis of such patients. Methods: The case of the peritoneal malignant mesothelioma was processed and reported in the routine manner for biopsy specimens at different stages. Results and conclusion: We report a case of a malignant tumor originating in the hepatorenal recess, which was diagnosed as biphasic malignant mesothelioma through a biopsy. Immunohistochemical testing showed PD-L1 expression. After multidisciplinary discussion, the patient received transformative treatment, including a trial of combined immunotherapy. The tumor significantly shrank, and the patient obtained a chance for curative surgical resection. Microscopic examination showed significant collagenization in the lesion area, with almost no residual tumor. After 19 months of comprehensive treatment, the patient developed multiple fluffy opacities under the pleura of both lungs. Transthoracic core needle biopsy under CT guidance, the pathology showed organizing pneumonia, considering it as delayed interstitial pneumonitis due to immunotherapy based on previous treatment history. Successful comprehensive treatment was achieved for this case of peritoneal malignant mesothelioma, and the patient has been alive without evidence of disease for 33 months, with long-term follow-up. In this process, the pathologist had three opportunities for pathological diagnosis, which required understanding the patient\'s medical history, being attentive to the clinical purpose of the specimen, and providing accurate responses to morphological changes at different stages, along with corresponding descriptions and diagnoses to provide effective information for clinical treatment.

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Metastatic thyroid cancer is rare. Here, the case of a patient with colon cancer that metastasized to the thyroid is described. The patient underwent radical rectal cancer surgery in August 2017 and received six cycles of chemotherapy with oxaliplatin and capecitabine postoperatively. On August 4, 2018, the patient was admitted to the hospital due to the discovery of thyroid nodules on ultrasound and carcinoembryonic antigen levels within the normal range. The biopsy from the fine needle aspiration suggested a malignant tumor. The patient underwent radical thyroid cancer surgery. Using intraoperative rapid frozen pathology, medullary carcinoma was diagnosed. Using postoperative routine pathology combined with immunohistochemistry results, thyroid metastasis from colorectal adenocarcinoma was diagnosed. After surgery, the patient regularly visited the outpatient clinic for chemotherapy with capecitabine. As of May 2023, the patient is still alive with no recurrence.

An ossifying fibromyxoid tumor is a soft tissue neoplasm with ambiguous differentiation and low metastatic potential. Most cases involve the lower extremities, followed by the trunk, the upper extremities, and the head and neck region. It mainly arises in 40-70 years of age, and men dominate the disease\'s gender distribution. In the described types of ossifying fibromyxoid tumors, there are three variants: one is benign (typical), the second is malignant, which carries the risk of disease recurrence or metastases, and the third is atypical, which does not meet the criteria of either typical or malignant. Here, we present an interesting case of a malignant ossifying fibromyxoid tumor of the chest wall that metastasized to the lungs even after complete resection of the primary tumor. A 64-year-old man had a 4.0 cm malignant ossifying fibromyxoid tumor in his chest wall two years ago, and at that time, the tumor was removed entirely. On pathology review, it was noted to have 20 mitotic figures per 50 high-power fields, but no actual grade was given. He was given postoperative radiation. His recent computed tomography (CT) chest with contrast showed a new right upper lung lobe nodule measuring 0.78 cm compared to the previous contrast-enhanced CT chest six months ago. It was worrisome for metastasis. F-18 FDG positron emission tomography scan revealed sub-centimetric pulmonary nodules in the right upper lobe. Right upper lobe lung biopsy showed spindle cell neoplasm morphologically consistent with the patient\'s known history of malignant ossifying fibromyxoid tumor. Biopsy demonstrated fragments of the bronchial wall and alveolated lung parenchyma with a focal spindle cell proliferation demonstrating a fibromyxoid matrix. The patient was referred to the oncologist for further management. In conclusion, aggressive malignant ossifying fibromyxoid tumors can be found in atypical locations, e.g., the chest wall. Therefore, early diagnosis is crucial because of the high chances of metastasis to distant organs (including the lung) even after complete resection of the primary tumor. Even in asymptomatic patients, it is necessary to complete long-term follow-up for recurrence and metastasis surveillance of ossifying fibromyxoid tumors. Early recognition of recurrence or metastasis can decrease morbidity and mortality and improve overall organ function and patient survival.

Corded and hyalinized endometrioid carcinoma (CHEC) is a morphologic variant of endo-metrioid adenocarcinoma. The tumor exhibits a biphasic appearance with areas of traditional low-grade adenocarcinoma merging directly with areas of diffuse growth composed of epithelioid or spindled tumor cells forming cords, small clusters, or dispersed single cells. It is crucial to distinguish CHEC from its morphological mimics, such as malignant mixed mullerian tumor (MMMT), because CHECs are usually low stage, and are associated with a good post-hysterectomy prognosis in most cases while the latter portends a poor prognosis. The patient reported in this article was a 54-year-old woman who presented with postmenopausal vaginal bleeding for 2 months. The ultrasound image showed a thickened uneven echo endometrium of approximately 12.2 mm and a detectable blood flow signal. Magnetic resonance imaging revealed an abnormal endometrial signal, considered endometrial carcinoma (Stage Ⅰ B). On hysterectomy specimen, there was an exophytic mass in the uterine cavity with myometrium infiltrating. Microscopically, most component of the tumor was well to moderately differentiated endometrioid carcinoma. Some oval and spindle stromal cells proliferated on the superficial surface of the tumor with a bundle or sheet like growth pattern. In the endometrial curettage specimen, the proliferation of these stromal cells was more obvious, and some of the surrounding stroma was hyalinized and chondromyxoid, which made the stromal cells form a cord-like arrangement. Immunostains were done and both the endometrioid carcinoma and the proliferating stroma cells showed loss of expression of DNA mismatch repair protein MLH1/PMS2 and wild-type p53 protein. Molecular testing demonstrated that this patient had a microsatellite unstable (MSI) endometrial carcinoma. The patient was followed up for 6 months, and there was no recurrence. We diagnosed this case as CHEC, a variant of endometrioid carcinoma, although this case did not show specific β-catenin nuclear expression that was reported in previous researches. The striking low-grade biphasic appearance without TP53 mutation confirmed by immunohistochemistry and molecular testing supported the diagnosis of CHEC. This special morphology, which is usually distributed in the superficial part of the tumor, may result in differences between curettage and surgical specimens. Recent studies have documented an aggressive clinical course in a significant proportion of cases. More cases are needed to establish the clinical behaviors, pathologic features, and molecular profiles of CHECs. Recognition of the relevant characteristics is the prerequisite for pathologists to make correct diagnoses and acquire comprehensive interpretation.

Placental transmogrification of the lung (PTL) is a very rare benign lung lesion. There are only about 40 cases reported in the literature. The imaging and histological features of PTL cases in the publication are various, most of which are cystic and a few of which are solid. Being extremely rare, the solid PTL is unknown to major pathologists and surgeons. We reported a case of solid PTL in the anterior mediastinum. The patient was a 52-year-old male with no history of smoking and without symptoms. During physical examination, chest CT revealed a circular low-density lesion with a maximum diameter of 2.9 cm beside the spine in the posterior basal segment of the left lower lobe of the lung. The wedge resection was performed by video-assisted thoracoscopy. Grossly, a round nodule was located underneath the visceral pleura. It was about 3.0 cm×3.0 cm×1.6 cm and the cut surface was grey-red, soft and spongy. Microscopically, the nodule was constituted of papillare, which resembled placental villi at low magnification. The axis of papillae was edema, in which some mild round cells with clear cytoplasm and CD10 positive staining aggregated and transitioned to immature adipocytes and amorphous pink materials deposited with a few of inflammatory cells infiltration. The surface of papillae was covered with disconti-nuous alveolar epithelium. Combined with the typical morphology and immunohistochemical characteristics of CD10 positive, the diagnosis was PTL. The patient was followed up for 1 year without recurrence and discomfort. So far, the pathogenesis of PTL is unclear. The major hypotheses include hamartoma, variant of emphysema and clonal hyperplasia of stromal cells. Based on the study of our case and publication, we speculate that the hyperplasia of stromal cells located in the alveolar septa might be the first step to form the solid PTL. With the progression of the disease, a typical unilateral cystic nodule develops as a result of secondary cystic degeneration due to the occlusive valve effect. Surgery is the only option for diagnosis and treatment of PTL. The clinician should make an individualized operation plan according to the clinical manifestations, location and scope of the lesion, and preserve the surrounding normal lung tissue as much as possible while completely removing the lesion. There is a favorable prognosis.