Figure 2: Histopathologic examination reveals diffuse lymphoid tissue exhibiting prominent follicles. Follicles show proliferation of vessels with thick, hyalinized walls. Mantle zones are composed of small lymphocytes in a concentric “onion-skin” pattern. Interfollicular zones show lymphocytes and monocytes interspersed with hyalinized fibrous tissue and vessels. Thymic remnants and heterotopic parathyroid tissue is also identified in surrounding adipose tissue.
Figure 1C
HISTORY The patient is a 49-year-old female who presented with a three-year history of a neck mass. The patient complained of fatigue and denied any weight loss, fever, chills, night sweats, abdominal pain, bleeding, or other symptoms. Her past medical history is positive for hypothyroidism diag- nosed 10 years prior, for which she is on thyroid replacement therapy. On physical exam, the area of her lower neck was enlarged; however, there was no tenderness to palpation. A CT was obtained that demonstrated a 3.7 x 2.2 cm soft tissue density within the superior mediastinum just below the thyroid of nonspecific etiology. A surgical biopsy was also obtained. DISCUSSION Castleman’s disease is an uncommon, benign lym- phoproliferative disorder characterized by hypervascular lymphoid hyperplasia. 1,7 Originally described in the medi- astinum by Castleman et al. in 1956, the disease can develop wherever lymph nodes are present. Approximately 70%
of Castleman’s disease is found within the mediastinum, making it the most common location. Ten to fifteen percent of cases are seen within the abdomen, retroperitoneum, and pelvis. Another 10%-15% is seen in the head and neck. Castleman’s has also been described in the extralymphatic tissues, including the lung, larynx, parotid gland, pancreas, and muscle. 2,4,6 The etiology is uncertain. It is thought to be inflammatory or hamartomatous in nature. 3,4 Castleman’s disease occurs at any age with a peak incidence in the third to fourth decade; however, the multicentric form usually affects older individuals. 2,4 Two distinct histologic variants exist. Themost common of which is the hyaline-vascular type, which accounts for 90% of cases. Histologically, it is identified by small lym- phoreticular follicles distributedwithin a hyalinized stroma (Figure 2). The plasma cell type, which is the second variant and accounts for only about 10% of cases, is distinguishable by larger lymphoreticular nodules that are separated by sheets of plasma cells and a less vascular stroma. 7 Castleman’s disease can also be categorized as either unicentric or multicentric. Typically, the unicentric variety is of the hyaline-vascular type and is amenable to surgical
J La State Med Soc VOL 166 March/April 2014 79
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