Mesothelial pelvic lymph node inclusions mimicking metastatic thyroid carcinoma

Mesothelial Cells Within Vascular Transformation of Mediastinal Lymph Node Sinuses: An Unusual Benign Collision Mimicking Colliding Malignancies

Vascular transformation of lymph node sinuses represents a rare benign entity mimicking malignant counterparts such as nodal Kaposi sarcoma. The presence of mildly atypical benign mesothelial cells within nodal sinuses raises the possibility of metastatic malignancy. Herein, a rare case of vascular transformation of lymph node sinuses with reactive sinusoidal mesothelial cells is outlined as a unique benign pathology and a potential mimicker of a malignant collision tumor.

Mesothelial pelvic lymph node inclusion in a patient with ovarian microinvasive borderline mucinous tumor: case report with review of the literature

The presence of mesothelial cell inclusions in lymph nodes is rare. Localization of these inclusions in abdominal and pelvic lymph nodes is an exceedingly rare event, with only eight cases reported. We report here a case of mesothelial cell inclusions in pelvic lymph node of a patient with ovarian microinvasive borderline mucinous tumor. This case differs from the previously reported cases for the following reasons. First, there was no evidence of serosal effusion. Second, it is the first reported case of nodal mesothelial inclusions in a patient with ovarian microinvasive mucinous borderline tumor. Last, histologically, mesothelial cell inclusions were accompanied by psammoma bodies. The potential problem of misdiagnosis as a metastatic tumor can be avoided by an awareness of these inclusions, supported by immunohistochemical results.

Benign pulmonary epithelial inclusions within the pleura: a case report

Background

The normal visceral and parietal pleura are composed of a mesothelium-lined layer of fibrous connective tissue, consisting predominantly of collagen and elastin fibers, with interspersed nerves, lymphatics, and blood vessels. There is no normal epithelial component to the pleura, and the histologic finding of epithelial cells within pleural tissue typically indicates the presence of a malignant process. The one documented exception to this rule is the occasional occurrence of endometriotic implants, which can result in cyclic thoracic symptomatology and occasionally even hemothorax.

Case Presentation

We present a case of seemingly benign epithelial inclusions within the pleura of a sixty year-old male patient who underwent exploratory thoracotomy and subsequent resection of bullous emphysematous blebs. Examination of the surgical specimen revealed well-defined nests of benign-appearing epithelial cells in glandular configurations at multiple sites within the pleura. These cells were immunopositive for TTF-1 and CK7 and immunonegative for calretenin, CK20, and CEA, indicating pulmonary epithelial derivation. Six months after resection, the patient is in stable health, with no clinical or radiologic evidence of bronchogenic carcinoma.

Conclusion

To our knowledge, this is the first report of benign pulmonary epithelial inclusions within pleural tissue. It is important to be aware that benign pleural inclusions occur, so as to avoid confusion with more serious processes in a population of patients who may have oncologic risk factors.

Assessment of pelvic lymph node micrometastatic disease in stages IB and IIA of carcinoma of the uterine cervix

The objective of this study was to assess the frequency of micrometastatic disease (MID) in pelvic lymph nodes (PLNs) in carcinoma of the uterine cervix (CUC) and to determine the risk of recurrence. The PLNs from 289 patients with CUC (IB and IIA) were studied. Each PLN was assessed via immunohistochemistry using a single histologic section (AE1/AE3). Metastatic deposits were measured and the disease status was classified into three groups: 1) absence of metastatic disease (MOD); 2) MID, one or more metastatic PLN with only isolated tumor cells and/or micrometastases (up to 2 mm); and 3) macrometastatic disease (MAD), presence of one or more metastatic PLN with macrometastases (more than 2 mm). Eleven patients (3.8%) were classified as having MID and 37 (12.8%) as having MAD. The 5-year disease-free survival (DFS) rates for MOD, MAD, and MID were 88.7%, 80.4%, and 50.0%, respectively (P < 0.001). The Cox proportional hazards model showed that MID was an independent variable for recurrence when adjusted for MAD, depth of tumor invasion, severity of inflammatory reaction, and use of adjuvant radiotherapy. We conclude that the frequency of MID in PLN was low. However, patients with MID presented a high risk of recurrence and reduced DFS.

Cellules épithéliales bénignes et protéine de Tamm-Horsfall dans les ganglions lymphatiques des pièces de néphrectomie pour néphroblastome : Un piège diagnostique

When a lymph node metastasis is discovered during the pathology examination of surgical specimens with nephroblastoma, the tumour is classified as stage III, according to the classification of the International Society of Paediatric Oncology (SIOP 2001), and post-operative intensive treatment of the patient includes irradiation and chemotherapy. Benign epithelial cells in perinephric lymph nodes in cases of renal tumours in childhood may be confused with metastases. They are often associated with an accumulation of Tamm-Horsfall protein in lymph node sinuses. This case illustrates latero-aortic lymph node complexes of benign epithelial cells and Tamm-Horsfall protein in a 16-month-old girl with surgical resection of a nephroblastoma after pre-operative chemotherapy. The nephroblastoma was predominantly epithelial and was classified as SIOP stage I. There were accumulations of Tamm-Horsfall protein in lymph node sinuses, in lymphatic vessels, in the kidney outside the tumour, and in the renal sinus. This association of epithelial cells with deposits of Tamm-Horsfall protein and their resemblance to cells of the distal convoluted tubules favour a diagnosis of benignity. A definitive diagnosis is supported by the small size of the cells, their bland nuclei, and morphological features differing from those of tumour cells, but deposits of Tamm-Horsfall protein may be associated with true lymph node metastases.

Fine-needle aspiration biopsy and intraoperative cytologic smear findings in a case of benign mesothelial-cell inclusions involving a lymph node: case report and review of the literature

Although first described over a decade ago, the rare entity of mesothelial lymph node inclusions (nonneoplastic mesothelial cells involving lymph node sinuses) is not well-known among pathologists. Unlike most lymph node inclusions such as Müllerian inclusions or nevus cells, which usually occur in the capsule of the lymph node, mesothelial cells involve the lymph node sinus, mimicking metastatic carcinoma or metastatic mesothelioma. The spectrum of histologic findings ranges from a few mesothelial cells, perhaps only detectable by immunohistochemical stains, to a massive distention of the lymph node sinus with abundant mesothelial cells. Mesothelial-cell inclusions in lymph nodes are usually found in mediastinal lymph nodes of patients with pleural and/or pericardial effusions. It is hypothesized that the effusion, due to whatever cause, allows for mesothelial-cell migration into the submesothelial lymphatics and regional lymph nodes. To our knowledge, cytologic findings on aspiration biopsy and intraoperative smear preparations of a lymph node with mesothelial-cell inclusions have never been described. Familiarity with this entity is important in preventing misdiagnosis of malignancy.

Extragenital adenomatoid tumor of a mediastinal lymph node

Adenomatoid tumors are benign neoplasms found predominantly in male and female genital tracts. Rare extragenital adenomatoid tumors have been discovered that involve serosal surfaces and nonmesothelial-lined organs such as adrenal glands. Since the discovery of adenomatoid tumors, their histogenetic origin has been debated. Many researchers support a mesothelial cell origin for adenomatoid tumors because these tumors characteristically express a mesothelial phenotype. Tumor derivation from primitive pluripotent mesenchymal cells and coelomic epithelium also has been suggested because of the anatomical distribution of the tumors. Despite their characteristic mesothelial phenotype and histological appearance, adenomatoid tumors have an extensive differential diagnosis that includes vascular neoplasms, malignant mesothelioma, germ cell tumors, and metastatic adenocarcinoma. Recognition of these tumors may be especially difficult when examined at frozen section and when adenomatoid tumors are encountered in rare extragenital sites. We describe an adenomatoid tumor of a mediastinal lymph node that was found incidentally during a redo Collis-Nissen gastroplasty. On frozen section examination, this tumor was misinterpreted as metastatic adenocarcinoma. The hematoxylin-eosin histological, immunohistochemical, and ultrastructural studies confirmed the mesothelial phenotype of this tumor. To our knowledge, this is the first description of a lymph node adenomatoid tumor.

Hyperplastic mesothelial cells in mediastinal lymph node sinuses with extranodal lymphatic involvement

We describe a patient with hyperplastic mesothelial cells localized to mediastinal lymph node sinuses. These mesothelial cells were originally misdiagnosed as metastatic carcinoma, and the patient received radiotherapy. Histologic review, immunohistochemistry, and ultrastructural studies confirmed mesothelial cell origin. These nodal mesothelial cells were associated with pericardial and pleural effusions. Extranodal lymphatics also contained hyperplastic mesothelial cells, confirming their mode of lymphatic transport to node sinuses. This finding supports the theory that hyperplastic mesothelial cells derive from reactive serosal mesothelium and are dislodged into draining lymphatics. This is the first report, to our knowledge, that demonstrates the pathogenetic significance of this lymphatic transport mechanism. Awareness of intralymphatic and nodal benign hyperplastic mesothelial cells and their mimicry of invasive malignant neoplasms is important for accurate diagnoses and appropriate therapy.