Thursday, February 28th, 2008.

Applied Immunohistochemistry & Molecular Morphology. 2008 Feb 8 [Epub ahead of print] [Link]

Wagner D, Bourne PA, Yang Q, Goldman BI, Lewis JS Jr, Xu H.

Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY †Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO.

Abstract

Malignant pleural mesothelioma (MPM) is a rare cancer that metastasizes to mediastinal lymph nodes (MLNs). The diagnosis of MPM metastatic to MLNs may not be straightforward. We describe 3 cases to highlight unusual entities of MPM metastatic to MLNs as follows. One patient with a history of T3N1M0, poorly differentiated esophageal adenocarcinoma and malignant melanoma presented with shortness of breath, mediastinal lymphadenopathy, and pleural effusion; metastatic disease was clinically suspected. Unexpectedly, immunohistochemical studies supported the diagnosis of MPM metastatic to the MLN on biopsy. In another case, mesothelial cell inclusions were initially diagnosed based on the light microscopy, immunohistochemistry, and lack of pleural thickening on computed tomography studies. Subsequent fine needle aspiration of an enlarged cervical lymph node found an atypical mesothelial proliferation, and metastatic mesothelioma was strongly suspected. Video-assisted thoracoscopic examination showed small visceral nodules, and pleural biopsy was diagnosed as malignant epithelioid mesothelioma. The mediastinal and cervical lymph node biopsies were reinterpreted as positive for MPM. In the last case, MLN biopsy showed a malignant epithelioid cell proliferation. Calretinin, CK5/6, WT-1, D2-40, p63, and CD5 were immunohistochemically detected in the tumor but epithelial markers and TTF-1 were negative. Metastatic mesothelioma was considered based on immunohistochemistry and computerized tomography finding of pleural thickening even though p63 and CD5 positivity were unusual. In summary, MPM may present as mediastinal lymphadenopathy with metastases or it may be a concurrent neoplasm with other malignancies or shows an unusual immunohistochemical staining pattern. Caution should be used when diagnosing mesothelial cell inclusions in MLNs.

Glossary

adenocarcinoma

(add-en-o car-sin-o-muh). Cancer that starts in the glandular tissue, such as in the ducts or lobules of the breast.

neoplasm

(nee-o-plas-um) an abnormal growth (tumor) that starts from a single altered cell; a neoplasm may be benign or malignant. Cancer is a malignant neoplasm.

needle aspiration

a type of needle biopsy. Removal of fluid from a cyst or cells from a tumor. In this procedure, a needle is used to reach the cyst or tumor, and with suction, draw up (aspirate) samples for examination under a microscope. If the needle is thin, the procedure is called a fine needle aspiration or FNA. (See also biopsy.)

melanoma

(mel-uh-no-muh) a cancerous (malignant) tumor that begins in the cells that produce the skin coloring (melanocytes). Melanoma is almost always curable in its early stages. However, it is likely to spread, and once it has spread to other parts of the body the chances for a cure are much less.

lymph nodes

small bean-shaped collections of immune system tissue such as lymphocytes, found along lymphatic vessels. They remove cell waste and fluids from lymph and help fight infections. Also called lymph glands.

lymph

(limf) clear fluid that flows through the lymphatic vessels and contains cells known as lymphocytes. These cells are important in fighting infections and may also have a role in fighting cancer.

immunology

(im-mune-ahl-o-jee) study of how the body resists infection and certain other diseases. Knowledge gained in this field is important to those cancer treatments based on the principles of immunology.

fine needle aspiration

see needle aspiration.

diagnosis

identifying a disease by its signs or symptoms, and by using imaging procedures and laboratory findings. The earlier a diagnosis of cancer is made, the better the chance for long-term survival.

cell

the basic unit of which all living things are made. Cells replace themselves by splitting and forming new cells (mitosis). The processes that control the formation of new cells and the death of old cells are disrupted in cancer.

cancer

malignancy; a group of diseases typified by abnormal, generally out-of-control, cell growth.

biopsy

(buy-op-see) the removal of a sample of tissue to see whether cancer cells are present. There are several kinds of biopsies. In some, a very thin needle is used to draw fluid and cells from a lump. In a core biopsy, a larger needle is used to remove more tissue.

atypical

(A-tip-uh-kul) not usual; abnormal. Often refers to the appearance of cancerous or precancerous cells. (See also hyperplasia.)

tumor

an abnormal lump or mass of tissue. Tumors can be benign (not cancerous) or malignant (cancerous).

mesothelioma

a tumor derived from mesothelial tissue, such as the peritoneum (lining the abdomen) or pleura (lining the lungs). More on mesothelioma.

pleural effusion

an abnormal accumulation of fluid, usually caused by trauma or disease, in the pleural space.

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