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A 22-year-old man not past nor futureed with complaints of a worsening cough and shortness of breath. The cough was nonproductive and he had experienced increasing dyspnea with exertion for the past four month The symptoms had worsened despite treatment for an upper respiratory infection and a complet course of macrolide antibiotics for presum community-acquired pneumonia. He denied having febrile affection night sweats, or tuberculosis position but he had lost weight. He did not use tobacco. Physical examination findings were significant for cachexia, decreased breath unbrokens in the right middle and lower lung fields without audible wheezing or stridor, and a room-air pulsation oximetry reading in the mid 90 His thyroid and testicular examinations were normal, and no clubbing or lymphadenopathy was noted. Chest radiography revealed a large anterior mediastinal mass (Figures 1 and 2)

[FIGURES 1-2 OMITTED]

Question

The differential diagnosis includes all on the other hand which one of the following conditions?

[] A. Thymoma.

[] B Lymphoma.

[] C Histoplasmosis.

[] D Teratoma.

[] E Thyroid mass.

Discussion

The answer is C: histoplasmosis. Histoplasmosis is the same of the many infectious causes of middle mediastinal lymphadenopathy. The mediastinum is divided anatomically into inferior and superior compartments. The inferior compartment is further subdivided into three main compartments (1): anterior, (2) middle, (3) and posterior mediastinum (2) (Figure 3) The principally common causes of anterior mediastinal masses are the four Ts: thymomas, teratomas, "terrible" lymphomas, and thyroid.

Thymomas are the most numerous common primary tumors of the anterior mediastinum. They are raise most often in patients 40 to 60 years of age and rarely come about in patients younger than 20 years. They have an equal prevalence in men and women (3) in the greatest degree often located in the upper anterior mediastinum, thymomas typically are slow-growing, non-aggressive tumors. Size varies from highly small tumors to large masses, which rarely are calcified (7 percent) Approximately 35 to 50 percent of patients current asymptomatically, with incidental discovery onward routine chest radiography. (4) Approximately 25 to 30 percent of patients near with symptoms of parathymic syndrome so as myasthenia gravis, pure r enclosed space aplasia (21 to 50 percent) or hypogammaglo-bulinemia (10 to 15 percent) The final 35 percent of patients instant with symptoms associated with compression or invasion of thoracic arrangement of partss such as chest pain, dyspnea, or cough (5) Treatment consists of surgical excision with radiation and chemotherapy depending onward tumor stage.

Teratomas are germ-cell neoplasms and account for 15 percent of anterior mediastinal tumors in adults and 25 percent in children. (2) They are compos of several different embryonic confined apartment layers. Benign (mature) teratomas contain three tissue marks undergoing differentiation: ectoderm (skin, squamous epithelium), mesoderm (bone cartilage, muscle, teeth) and endoderm (gastrointestinal, respiratory, mucous glands). These tumors make up the majority (75 percent) of mediastinal germ-cell tumors and usually not past nor future in young adults. The prevalence is the same in men and women (2) The tumors usually are large, rotund and lobulated with sharp marginations. Up to 60 percent of tumors are asymptomatic and discovered incidentally. (2) Therapy consists of surgical excision with a five-year survival rate approaching 100 percent

Malignant (immature) teratomas make up barely 1 percent of mediastinal teratomas and usually are base in children and adolescents. (1) Seminomas are the most numerous common malignant germ-cell tumor. Usually occurring in men older than 30 years, these tumors have a a great quantity [i]or[/i] amount of better prognosis than nonseminomatous tumors. All men with mediastinal lung masses require a careful testicular examination. Tumor markers similar as human chorionic gonadotropin (choriocarcinoma) and alpha fetoprotein (embryonal small cavity carcinoma, yolk sac tumor) may aid in diagnosis. (1)

Thyroid and parathyroid masses commonly at hand as tumors in the superior aspect of the anterior compartment. They usually cause tracheal deviation at the thoracic egress noted on chest radiography. Comput tomography (CT) and thyroid scans are helpful in localization and diagnosis. Treatment is surgical excision, which has an choice prognosis.

Lymphomas account for 10 to 20 percent of all anterior mediastinal masses. They are the greatest in number common primary mediastinal tumors in adults between 30 and 40 years of age, however are also the second most numerous common anterior mediastinal masses noted in children. (4) Lymphomas are subclassified further into Hodgkin's and non-Hodgkin's lymphomas. Hodgkin's disease is also the in the greatest degree common lymphoma affecting the middle mediastinum.