A 65-year-old man comes to the office due to several weeks of nonproductive cough. The patient also has anorexia and unintentional weight loss. His medical history includes hypothyroidism due to Hashimoto thyroiditis and a 50-pack-year smoking history. Examination shows an enlarged right supraclavicular lymph node. Imaging reveals a large mediastinal mass causing tracheal deviation. The enlarged node is biopsied, and microscopy demonstrates clusters of small, ovoid cells with scant cytoplasm and a high mitotic count. Immunohistochemical staining is positive for chromogranin. This patient most likely has which of the following conditions?

Question

A 65-year-old man comes to the office due to several weeks of nonproductive cough.  The patient also has anorexia and unintentional weight loss.  His medical history includes hypothyroidism due to Hashimoto thyroiditis and a 50-pack-year smoking history.  Examination shows an enlarged right supraclavicular lymph node.  Imaging reveals a large mediastinal mass causing tracheal deviation.  The enlarged node is biopsied, and microscopy demonstrates clusters of small, ovoid cells with scant cytoplasm and a high mitotic count.  Immunohistochemical staining is positive for chromogranin.  This patient most likely has which of the following conditions?

Quizplus · Accepted Answer

11ec160b_3a14_4197_9249_9fbc13924772_MD0001_00 This patient with a heavy smoking history, weight loss, cough, and a mediastinal mass with evidence of metastases (ie, supraclavicular node elargement) has small cell lung cancer (SCLC), also known as oat cell carcinoma. SCLC makes up 10%-20% of all primary lung malignancies and is strongly associated with smoking. It is usually centrally located and arises from the primitive cells of the basal layer of the bronchial epithelium. On light microscopy, small, round or oval cells with scant cytoplasm, hyperchromatic (blue) nuclei, and granular chromatin are visualized. The cells, which may resemble lymphocytes but are typically larger, form clusters or sheets. Abundant mitoses are usually seen. Small cell carcinomas can display varying degrees of neuroendocrine differentiation. Immunohistochemical stains are frequently positive for neuroendocrine markers, such as neuron-specific enolase, chromogranin, neural cell adhesion molecule (CD56), and synaptophysin. On electron microscopy, some of the cells have secretory granules in the cytoplasm. (Choice A) Adenocarcinoma is the most common form of cancer in both nonsmokers and the total population. It is histologically characterized by glandular differentiation (eg, gland formation, mucin production), and the tumor cells often show abundant cytoplasm and eccentrically placed nuclei. The cells often stain positive for mucin. It typically arises in the periphery of the lung. (Choice B) Hodgkin lymphoma typically presents with cervical lymphadenopathy and can cause a mediastinal mass. However, microscopy demonstrates Reed-Sternberg cells (large cell with multilobed nucleus or multiple nuclei, prominent nucleoli, abundant cytoplasm, and an "owl's eye" appearance) in a background of inflammatory cells. In addition, other B symptoms (eg, fever, night sweats) are common. (Choice C) Papillary thyroid carcinoma presents with a thyroid nodule and cervical lymphadenopathy but can also cause an anterior mediastinal mass. Histology reveals branching papillae, which are composed of a fibrovascular stalk covered by neoplastic cuboidal cells with clear ("ground-glass") nuclei. Psammoma bodies (laminated calcium deposits) can sometimes be seen. (Choice E) Squamous cell carcinoma typically arises centrally and is composed of polygonal cells with eosinophilic cytoplasm and distinct borders. Well-differentiated squamous cell carcinomas show keratin pearls and intercellular bridges on light microscopy. Educational objective: Small cell lung cancer is strongly associated with smoking and is usually centrally located. Histopathology shows small round/oval cells with scant cytoplasm, hyperchromatic (blue) nuclei, and granular chromatin; abundant mitoses are also usually seen. Immunohistochemical stains are frequently positive for neuroendocrine markers (eg, chromogranin, synaptophysin, neural cell adhesion molecule [CD56]).

A 65-Year-Old Man Comes to the Office Due to Several