IUHS Student-2-Student USMLE Step 1 Recall
Respiratory
Lung Tumors
Squamous Cell Carcinoma of the Lung
Cells with hyperchromatic nuclei and dense orange-pink cytoplasm...
stains bright red on pap smear...
most commonly found in men and is closely correlated with a smoking history...also, radon...
microscopic features are familiar in the form of production of keratin ("squamous pearls") and intercellular bridges (desmosomes) in the well-differentiated forms, but many less well differentiated squamous cell tumors are encountered that begin to merge with the the undifferentiated large cell pattern...
hilar mass, this tumor arises in the larger, more central bronchi, tends to spread locally, and metastasizes somewhat later than the other patterns...more rapid growth in its site of origin is usually rapid than that of other types...
squamous metaplasia, epithelial dysplasia, and foci of frank carcinoma in situ are sometimes present in bonchial epithelium adjacent to the tumor mass...
associated with hypercalcemia...
also, associated with Parathyromone (PTH)...considered to be parathyroid homrone-related peptide...
Most squamous cell carcinomas are located centrally and arise in bronchi, leading to obstruction that can cause a lipid pneumonia. In this case, the breakdown of lung tissue distal to the mass yields an 'endogenous lipid pneumonia.
Adenocarcinoma
two classifications, bronchial-derived adenocarcioma and bronchioloalveolar carcinoma...
adenocarcinoma is the most common type of lung cancer in women and nonsmokers...lesions tend to be more peripherally located, tend to be smaller, and vary histologically from well-differentiated tumors with obvious glandular elements to papillary lesions resembling other papillary carcinomas, to solid masses with only occasional mucin producing glands and cells...
about 80% contain mucin...adenocarcinomas grow more slowly than squamous cell carcinomas...
peripheral adenocarcinomas are sometimes associated with areas of scarring...
adenocarcinomas, including bronchioloalveolar carcinomas, are less frequently associated with a history of smoking (still >75% found in smokers) than are squamous or small cell carcinomas...
K-ras is the common oncogene...
acanthosis nigricans often manifests before the onset of symptoms associated with adenocarcinoma...
Small Cell Carcinoma
L-myc
oncogene
is the common genetic mutation...
bombesin is a peptide found with small cell carinoma...
highly malignant tumor has a distinctive cell type...the epithelial cells are generally small, have little cytoplasm, and are small, round, and oval and, lack nucleoli...
this is the classic oat cell...other small cell carcinomas have spindle-shaped or polygonal cells and may be thus classified (spindle or polygonal small cell carcinoma)...the cells grow in clusters that exhibit neither glandular nor squamous organization...
microscopic studies show dense-core neurosecretory granules in some of these tumor cells...the granules are similar to those found in the neuroendocrine argentaffin cells present along the broncial epithelium, particularly in the fetus and neonate...cells have properties of APUD (amine prescursor uptake and decarboxylation) cell type...
small cell carcinomas have the ability to secret polypeptide hormones and the presence of neuroendocrine markers such as neuron-specific enolase and parathormone-like and other hormonally active products suggest derivation of this tumor from neuroendocrine cells of the lining bronchial epithelium...
small cell carcinomas have a strong relationship to cigarette smoking, only about 1% occur in non-smokers...
most often hilar or central, or likely peripheral, they are the most aggressive of the lung tumors, metastasize widely, and are virtually incurable by surgical means...
Pareneoploatic Syndromes...they are most common pattern associated with ectopic hormone production...ACTH and ADH...which causes low sodium...hyponatremia...
Lambert-Eaton Myasthenic Syndrome is caused by Small Cell Carcinoma...
Superior Vena Cava Syndrome is often seen in small cell carcinoma of the lung...presents as engorgement of neck veins and veins over right chest wall...retinal vein engorgement...complains of headache and visual disturbances...
Too rapid correction of hyponatremia can lead to Central Pontine Myelinosis. He probably had a syndrome of inappropriate ADH with an oat cell carcinoma of the lung.
Large
Cell Carcinoma
this anaplastic carcioma has larger, more polygonal cells and vesicular nuclei...
large cell carcinomas probably represent squamous cell carcinomas and adenocarcinomas that are so undifferentiated that they can no longer be recognized...
some of these large cell carcinomas contain intracellular mucin, some exhibit larger numbers of multinucleate cells (giant cell carcinoma), some have cleared cells and are termed clear cell carcinoma, and some have a distinctly spindly histologic appearance (spindle cell carcinoma)...
Pancoast Tumors
apical lung cancers in the superior pulmonary sulcus tend to invade the neural structures around the trachea, including the cervical sympathetic plexus, and produce a group of clinical findings that include severe pain in the distribution of the ulnar nerve and Horner syndrome (enophthalmos, ptosis, miosis, and anhidrosis) on the same side as the lesion...
such tumors are also referred to as Pancoast Tumors...
Bronchioloalveolar Carcinoma
occurs
in the pulmonary parenchyma in the terminal bronchioloalveolar regions...it
represents 1-9% of all lung cancers...
this tumor almost always occurs in the peripheral portions of the lung either as a single nodule or, most often, as multiple diffues nodules that sometimes coalesce to produce a pneumonia-like consolidation...
the parenchymal nodules have a mucinous, gray translucence when secretion is present and otherwise appears as solid, gray-white areas that can be confused with pneumonia on casual inspection...
histologically, the tumor is characterized by distinctive, tall, columnar-to-cuboidal epithelial cells that line up along alveolar septa and project into the alveolar septa and project into the alveolar spaces in numerous branching papillary formation...tumor cells often contain abundant mucinous secretions...
the degree of anaplasia is quite variable, but most tumors are well differentiated and tend to preserve the native septal wall architecture...
bronchioloalveolar carcinomas are a heterogeneous group, consisting of mucin-secreting bronchiolar cells, Clara cells, or, rarely, type II pneumocytes...
Horners Syndrome
horner's syndorme, which results from interruption of the sympathetic innervation to the head and neck , may be caused by lung cancers located in the upper lobes of the lung that invade the sympathetic pathway...
symptoms associated with Horners Syndrome include ipslateral lack of sweating (anhidrosis), abnormal pupillary constriciton (miosis), and drooping (ptosis) of the eyelid...
these apical lung tumors can also involve the eighth cervical and first and second throacic nerves to produce shoulder pain that radiates to the arm in an ulnar distribution (pancoast tumor)...
a lesion of the cervical sympathetic plexus of the spinal cord is most likely to produce horners syndrome....
Hamartomas in the Lung
pulmonary hamartomas, although infrequent, are still the most common of all benign lung tumors...
hamartomas consist of various tissues normally found in the organ where they develop, but in abnormal amounts and arrangements...
in the lung they consist of lobules of connective tissue often containing mature cartilage, fat, or fibrous tissue and seperated by clefts lined by entrapped respiratory epithelium...
the peak incidence is at age 60, and the tumor is usually found as a well circumscribed, peripheral "coin" lesion on routine chest x-ray...
unless radiographic findings are pathognomic of hamartoma with "popcorn ball" calcifications, the lesion should be excised or at least carefully followed...
conservative excision is curative...
hamartoma is very firm and obtaining aspirated material will be difficult...