Archive by category 'Surgpedia'
February 13th, 2010
Pathophysiology
1) neoplasm originating in retinal neurons 2) malignant spread is either via the optic nerve into the cranial vault or via the blood system (hematogenously) 3) able to grow toward vitreous body (endophytic) or between retinal layers (exophytic)
Signs and Symptoms
1) white pupil reflex (leukocoria) 2) red and painful eye 3) squinting 4) vision loss 5) detached retina 6) cat’s eye reflex (yellowish glint in eye)
Characteristic Test Findings
Funduscopic exam – 1) mass 2) detached retina
Histology/Gross Pathology
1) whitish tumor mass with chalk-like flecks (calcification) 2) morphologically can have Flexner-Wintersteiner rosettes (radial cells around central cavity) or a fleur-de-lis pattern
Associated Conditions
1) secondary glaucoma in affected eye 2) metastasizes to bone marrow 3) inherited form – increase incidence in Ewing’s sarcoma, pinealoblastoma, and osteogenic sarcoma
Inheritance/Epidemiology
1) occurs in 1: 20,000 to 1:34,000 2) presents at birth or in first 2 years of life 3) most cases sporadic, but 6-8% familial 4) bilateral 30% of time in familial disease 5) cause is defect in retinoblastoma tumor suppressor gene on 13q14
Treatment
if treated early with enucleation, survival rate is 90%
Tips for USMLE
if a 2 year old girl has been squinting for the past 2 weeks and then starts rubbing a reddish left eye that has a milky tint to the pupil, think retinoblastoma
February 13th, 2010
Pathophysiology
1) malignant tumor of neural crest origin, from adrenal medulla or sympathetic ganglia 2) 33% of tumors occur in adrenals, 33% in abdomen, 20% in posterior mediastinum 3) metastasizes to regional lymph nodes, lungs, bone, liver, eye
Signs and Symptoms
1) common presenting sign is an enlarging abdominal mass with calcification 2) ascites from liver metastases 3) pain and irritability from bone metastases 4) respiratory distress from lung compression 5) gait and sphincter problems
Characteristic Test Findings
Laboratory – 1) increased urinary catecholamines – norepinephrine, VMA, HVA, dopamine 2) increased secretion of VIP
Histology/Gross Pathology
1) differentiating neuroblasts (small, round, blue cells) 2) mature ganglion cells (more mature tumors have higher proportion of ganglion cells) 3) rosettes and pseudorosettes (Homer-Wright rosettes)
Associated Conditions
1) deletions on chromosome 1 (1p35-36) 2) duplications on chromosome 2 3) affected gene is N-myc (which can be amplified, depending on differentiation
Inheritance/Epidemiology
1) mostly sporadic inheritance 2) 10% of childhood cancers 3) usually occurs before age 3 years 4) best prognosis – presents < age 2 years, extra-adrenal location, highly differentiated, VMA/HVA > 1, TRK gene expression
Treatment
1) if isolated mass, surgical resection 2) if metastatic, chemotherapy/radiation
Tips for USMLE
1) if question mentions a 2 month-old child with a large abdominal mass (with calcification on radiograph) that suddenly shrinks, think neuroblastoma 2) neuroblastomas “cross the midline,” whereas Wilms’s tumors do not
Related Posts
Retinoblastoma
February 13th, 2010
Pathophysiology
1) tumor of arachnoid cells of meninges 2) usually attached to dura 3) may invade skull but rarely invades brain tissue 4) found most commonly along dorsal surface of spinal cord, along sagittal sinus, over cerebral convexities, and at the cerebellar-pontine angle
Signs and Symptoms
1) occasionally, is asymptomatic and found incidentally 2) symptoms are generally caused by mass effect 3) focal seizures 4) focal neurologic findings 5) increased intracranial pressure 6) loss of smell (if located in frontal lobes) 7) visual defects of optic neuropathy in one eye and hemianopia in the other if located anterior to chiasm
Characteristic Test Findings
Radiology – 1) well-circumscribed, intensely contrast-enhancing lesion on CT and MRI 2) “dural tail” of contrast streak may be seen on CT scan 3) commonly associated with hyperostosis of skull
Histology/Gross Pathology
1) arises from meningothelial cells of arachnoid 2) most tumors are in intimate contact with dura 3) well-circumscribed tumors with whorls of spindle cells and psammoma bodies
Associated Conditions
neurofibromatosis types 1 and 2
Inheritance/Epidemiology
1) second most common primary brain neoplasm after astrocytoma 2) uncommon in children 3) rarely can be overtly malignant
Treatment
1) resection for cure, if possible 2) if not easily approached surgically, local external beam radiation, or gamma-knife radiation is used 3) if small and asymptomatic in an elderly patient, it can be observed with serial CT scans, as tumors are very slow growing
Tips for USMLE
if brain tumor appears to be attached to the dura, think meningioma
Related Posts
Astrocytoma
February 13th, 2010
Pathophysiology
1) psychiatric disorder marked by unpredictable swings in mood from mania to depression 2) variants exist where there are repeated manic episodes without the intervening depressive episodes and vice versa 3) rapid cycling variant – four or more episodes of mania or depression per year
Signs and Symptoms
Manic phase – 1) increased psychomotor activity 2) decreased need for sleep 3) excessive social extroversion 4) impulsive actions 5) irritability 6) grandiose delusions 7) paranoia Depressive phase – 8) loss of interest in life or surroundings 9) decreased libido 10) significant weight gain or loss 11) feelings of fatigue and tiredness 12) sleep disturbances 13) feelings of hopelessness and intense sadness
Characteristic Test Findings
Radiology – abnormally high incidence of subcortical white matter abnormalities
Associated Conditions
1) strong genetic predisposition (30% concordance rate in monozygotic twins) 2) altered circadian rhythms
Biochemistry
exact underlying biology is unknown but may involve alterations in glutamate regulation
Inheritance/Epidemiology
1) affects 3 million people in USA 2) occurs roughly equally in men and women, but men have more manic episodes and women have more depressive episodes 3) age of onset is most common in late teens to age 30 4) prognosis is mixed, with 50% of patients unable to function normally in work and psychosocial roles even with treatment
Treatment
1) lithium and valproate are mainstays of treatment 2) common adjunctive drugs – carbamazepine and lamotrigine 3) antidepressants – used if depressive phase is severe but should not be started in maintenance phase, as they may precipitate a manic breakthrough
Tips for USMLE
if a 23 year old man returns home from graduate school and excitedly tells his family that he is quitting school because he has founded a company that he is sure will revolutionize the computer industry and he is so confident of his success that he has purchased (on credit) a Mercedes Benz and 500 bottles of expensive wine, think bipolar disease
Related Posts
Obsessive Compulsive Disorder
February 13th, 2010
Pathophysiology
1) depressed mood daily for a minimum of 14 days 2) not associated with general medical condition or bereavement
Signs and Symptoms
1) diminished pleasure or interest in daily activities 2) sadness, thoughts of death, suicidal ideation 3) irritability 4) feelings of hopelessness or worthlessness 5) insomnia or hypersomnia 6) early morning awakening 7) fatigue 8) weight loss or gain 9) decrease in concentration and/or ability to make decisions
Characteristic Test Findings
Laboratory – 1) decreased plasma tryptophan 2) increased plasma cortisol Radiology – 3) PET scan shows decreased glucose metabolism in caudate nucleus and frontal lobes
Histology/Gross Pathology
decreased noradrenergic neurons in locus ceruleus
Associated Conditions
1) suicide (15%) 2) bipolar disease 3) trauma or assault 4) seasonal affective disorder 5) decreased REM sleep onset (latency)
Biochemistry
1) decreased serotonin levels 2) involvement of prefrontal cortex and basal ganglia in abnormal neurotransmitter functioning
Inheritance/Epidemiology
1) affects 15% of USA population sometime in lifetime 2) female to male, 2:1 3) incidence increases with age 4) 45% concordance rate in identical twins
Treatment
1) selective serotonin reuptake inhibitors (fluoxetine, sertraline, paroxetine) 2) tricyclic antidepressants (nortriptyline) 3) monoamine oxidase inhibitors (no longer first-line treatment owing to hypertensive crisis that arises with ingestion of tyramine-containing substances 4) psychotherapy 5) electroconvulsive therapy in drug-resistant cases
Tips for USMLE
if a 50 year-old woman has lost 25 pounds from “losing her appetite”, reports “feeling like her life has been a waste” and is thinking of suicide, and reports waking up at 4 am each morning without being able to get back to sleep, think depression
Related Posts
Obsessive Compulsive Disorder
February 13th, 2010
Pathophysiology
1) compulsive behavior and/or obsessive thoughts that impair everyday functioning 2) usually occurs for at least one hour a day
Signs and Symptoms
1) repetitive handwashing 2) repetitive counting 3) checking repeatedly as to whether a task has been accomplished 4) fear of germs or contamination 5) repetitive hair pulling (trichotillomania) with bald spots or missing eyebrows or lashes 6) wish to conceal their compulsion 7) feeling of anxiety if compulsive behavior is denied 8) tends to have a prolonged and waxing and waning course
Characteristic Test Findings
Radiology – positive PET scan findings in caudate nucleus and frontal white matter (PET scans “light up positive) in areas that have high glucose metabolism)
Histology/Gross Pathology
1) decreased size of caudate nucleus 2) abnormal frontal lobe white matter
Biochemistry
increased glucose metabolism in head of caudate nucleus and orbital cortex of frontal lobes
Associated Conditions
Tourette’s disorder
Inheritance/Epidemiology
1) lifetime prevalence is 2% worldwide 2) onset is usually in early adulthood but adolescent onset does occur 3) more common in males and firstborn 4) familial predisposition does occur with increased concordance in monozygotic twins
Treatment
1) drugs – fluoxetine, fluvoxamine (sometimes in combination with buspirone and benzodiazepine) 2) behavior therapy – with gradual increase in stressors and substitions of less disruptive activity for compulsions
Tips for USMLE
if the patient is a 23 year old man who cannot start work in the morning without washing off the surface of his desk exactly 17 times, think obsessive compulsive disorder
Related Posts
Panic Disorder
February 13th, 2010
Pathophysiology
1) a group of 20 conditions all marked by clonal neoplastic transformation of lymphoid cells 2) initial phase involves infiltration of lymph nodes with a variable secondary leukemic phase in which malignant cells circulate in the bloodstream 3) can be either of B cell (90% of patients) or T cell origin 4) classified as low-grade or indolent (small cell or mixed cell), intermediate grade, or high grade (large cell or lymphoblastic)
Signs and Symptoms
1) fever and night sweats 2) painless adenopathy 3) enlarged spleen 4) enlarged liver
Histology/Gross Pathology
1) lymph nodes have a pale color on cut surface 2) obliteration of normal lymph node architecture with white pulp enlargement 3) adults – 40% of patients have a follicular/nodular pattern of lymph node involvement (better prognosis) and 60% have a diffuse pattern 4) children – virtually all patients have the diffuse pattern 5) infiltration of spleen, liver (discrete nodules occur in intermediate and high-grade neoplasms), and bone marrow occurs 6) some children have a “starry sky pattern” of lymph node infiltrate.
Associated Conditions
increased incidence with – 1) organ transplantation 2) HIV/AIDS 3) rheumatoid arthritis 4) sicca syndrome 5) Sjogren’s syndrome 6) Chediak-Higashi disease 7) Wiskott-Aldrich disease 8) ataxia telangiectasia 9) IgA deficiency 10) celiac disease 11) post-treatment for Hodgkin’s disease 12) lupus 13) Klinefelter’s syndrome 14) dioxin exposure 15) treatment with alkylating agents 16) herbicides 17) benzene
Biochemistry
1) Burkitt’s lymphoma – associated with Ebstein-Barr virus 2) follicular small cell cleaved variant – associated wtih bcl-2 gene and translocation of chromosomes 14 and 18 3) mature T cell lymphoma – associated with hypergammaglobulinemia 4) low-grade B cell variant – associated with monoclonal immunoglobulin
Inheritance/Epidemiology
1) increased in frequency in USA in past 50 years 2) slightly more common in men 3) median age of onset is 50 years
Treatment
1) chemotherapy 2) radiation
Tips for USMLE
if question mentions a 68 year-old man with a 2 month history of night sweats, fever, and painless adenopathy in the left axilla, think of a non-Hodgkin’s lymphoma
Related Posts
Non-Hodgkin’s Lymphoma
Burkitt’s Lymphoma
Ataxia-telangiectasia
February 13th, 2010
Pathophysiology
1) neoplasm that produces bone (both mineralized and unmineralized) 2) most common in long-bone metaphyses (proximal humerus and tibia and distal femur) 3) metastases are to lung and skeleton
Signs and Symptoms
1) pain and enlargement of affected area 2) fever
Characteristic Test Findings
Radiology – 1) Codman’s triangle (new bone formation at margin of soft tissue) 2) sunburst appearance (spiculations in reactive periosteal tissue) 3) mass lesion with moth-eaten appearance
Histology/Gross Pathology
1) hypervascular, spindle-cell neoplasm 2) main subtypes – fibroblastic, chondroblastic, osteoblastic 3) rarer subtypes – malignant fibrous histiocytosis, telangiectatic, small cell, and epitheliod
Associated Conditions
1) radiation therapy 2) Paget’s disease
Inheritance/Epidemiology
1) 70% occur at age 10-30 years 2) at ages 40-60 occurs as malignant transformation (of Paget’s disease, in radiated tissues) 3) male to female, 2:1
Treatment
preoperative chemotherapy (doxorubicin, ifosfamide, cisplatin), surgical resection (limb-sparing if possible), postoperative chemotherapy
Tips for USMLE
1) osteosarcomas are radiation resistant 2) if Codman’s triangle is mentioned, think osteosarcoma 3) if “sunburst” tumor is mentioned, think osteosarcoma
February 11th, 2010
Pathophysiology
1) neoplastic transformation of the ovaries (can be malignant or benign) 2) classified by cell origin of abnormal growth – epithelial (70%), sex cord stromal (5%-10%), or germ cell (15%-20%) tumors
Signs and Symptoms
1) abdominal pain 2) bloating 3) urinary frequency 4) constipation 5) palpable pelvic mass on gynecologic exam 6) granulosa cell tumor (type of sex cord stromal tumor) causes vaginal bleeding and precocious puberty 7) Sertoli/Leydig cell tumors cause virilization and hirsuitism 8) generally do not become symptomatic until late stage
Characteristic Test Findings
Laboratory – 1) presence of CA-125 tumor marker (occurs in 85% of patients, but very controversial when used as a screening test because other conditions cause increased levels) 2) increased serum levels of alpha fetoprotein (AFP) in germ cell tumors 3) presence of beta-HCG in germ cell tumors 4) increased serum androgens in Sertoli/Leydig cell tumors Radiology – 5) mass on ovary in vaginal and/or abdominal ultrasound
Histology/Gross Pathology
1) epithelial subtypes – serous, mucinous, endometroid, clear cell, Brenner tumors 2) sex cord stromal subtypes – granulosa cell, theca cell, Sertoli’s cell, Leydig’s cell, and collagen-producing tumors 3) germ cell subtypes – teratomas, dysgerminoma, and endodermal sinus (yolk sac) tumors
Associated Conditions
increased incidence with – 1) nulliparity 2) infertility 3) clomiphene use 4) frequent miscarriages 5) family history of ovarian cancer 6) presence of BRCA1 and/or BRCA2 genes 7) Lynch’s syndrome (nonpolyposis colorectal cancer, endometrial cancer, ovarian cancer) 8) oncogenes c-myc, H-ras, K-ras, and neu
Inheritance/Epidemiology
1) 23,000 new cases in USA yearly 2) epithelial and some sex cord stromal tumors (Sertoli/Leydig cell tumors) are unusual before age 40 years 3) germ cell tumors and granulosa and theca cell tumors usually occur before age 30 years
Treatment
Surgery – 1) epithelial and sex cord stromal tumors – TAHBSO, omentectomy, biopsy of pelvic and periaortic nodes, and inspection of paracolic gutters with a “second-look” surgery after chemotherapy 2) germ cell tumors – removal of affected ovary only and no second look surgery Chemotherapy – 3) not for low-grade, stage 1 tumors 4) platinum-based with paclitaxel in epithelial and germ cell tumors; bleomycin-based in sex cord stromal tumors
Tips for USMLE
1) Krukenberg tumors are not primary ovarian tumors but rather metastatic “drop” tumors from the GI tract – classically described as originating in the stomach 2) if a 47 year-old woman who tried fertility drugs for 7 years develops diffuse lower abdominal pain, urinary frequency, and has a palpable mass on bimanual gynecologic exam, think ovarian cancer 3) CA-125 is usually followed post-treatment to see if tumor has recurred 4) germ cell tumors do not generally require removal of both ovaries and uterus, and fertility can be preserved.
February 10th, 2010
Pathophysiology
1) primary brain tumor dervied from astrocytes 2) wide variation in differentiation – grade 1 (astrocytoma), grade 2 (anaplastic astrocytoma), grade 3 (glioblastoma multiforme)
Signs and Symptoms
1) headaches (especially on waking) 2) vomiting 3) confusion leading to obtundation and coma 4) seizures 5) transtentorial (with fixed and dilated pupils due to CN III damage) or foramen magnum herniation
Characteristic Test Findings
Radiology – 1) poorly demarcated mass on MRI and CT scan 2) grade 3 – often crosses the midline and assumes “butterfly shpae” 3) grade 3 often with hemorrhage and frequent necrosis
Histology/Gross Pathology
Grade 1 – 1) well-differentiated astrocytes with a matrix of thin glial processes; but, grossly, tumor is poorly demarcated 2) occurs in cerebellum and midbrain in children (pilocytic subtype is cystic) and cerebrum in adults 3) some subtypes have Rosenthal’s fivers (thick eosinophilic fibers) Grade 2 – 4) increasing cellular pleomorphism Grade 3 – 5) endothelial cell proliferation in “glomeruloid” pattern 6) marked cellularity 7) serpentine areas of necrosis surrounded by “palisading” cells 8) areas of hemorrhage with red and yellow butterfly tumor
Biochemistry
1) if grade 3 tumors arise de novo, they are associated with a gene defect of amplification of epidermal growth factor receptors 2) if grade 3 tumor arises from a pre-existing grade 1 or 2, it is associated with the p53 or INK4a gene alterations
Inheritance/Epidemiology
1) life expectancy – 5 years for grade 1, 3 years for grade 2, and 9-12 months for grade 3 2) occasionally, the pilocytic subtype of grade 1 tumors can be resected for cure 3) grade 1 tumors mostly occur in children 4) grade 3 tumors are the most common intracranial primary tumor
Treatment
1) surgery for resection for cure (unlikely) or debulking 2) focused external beam radiation 3) sterotactic radiation with gamma knife 4) glucocorticoids 5) chemotherapy with nitrosureas (carmustine, lomustine) 6) many experimental therapy trials are underway with catheter based therapies
Tips for USMLE
1) astrocytomas almost never metastasize outside the CNS 2) if a 76 year old man with no medical problems has been having headaches every morning for the past month, now wakes up acutely confused, and has an MRI that shows a lesion in his frontal lobes in the shape of a butterfly, think glioblastoma multiforme.
|