Question 1.
A 17-year-old girl comes to her primary care provider’s office because of easy bruising. She reports having to quit her volleyball team because she has dislocated a joint each season that she has played. Physical examination shows old ecchymosis along her arms and legs. Her skin is hyperextensible and her thumb can be passively extended to her forearm as shown below:Which of the following is the most likely diagnosis?
Chediak-Higashi syndrome
Chediak-Higashi syndrome is a defect in microtubule polymerization that results in recurrent pyogenic infections, peripheral neuropathy, and partial albinism. Problems with microtubule polymerization can lead to decreased fusion of lysosomesand phagosomes.
Ehlers-Danlos syndrome
Major takeaway
Ehlers-Danlos syndrome is an inherited disorder of faulty collagen synthesis. Symptoms of Ehlers-Danlos syndrome include hyperextensible skin, hypermobile joints, easy bruising, organ rupture, and joint dislocation.
Main explanation
Ehlers-Danlos syndrome is an inherited disease of defective collagen synthesis. Depending on the sub-type of Ehlers-Danlos syndrome, the disease can either be autosomal dominant or recessive. Ehlers-Danlos can be sub-divided into several different types including classic (collagen type V), hypermobility, vascular (collagen type III), kyphoscoliosis, arthrochalasia, and dermatosparaxis Ehlers-Danlos syndrome. Symptoms of Ehlers-Danlos syndrome include hyperextensible skin, hypermobile joints, easy bruising, berry aneurysms, organ rupture, joint dislocation, and mitral valve prolapse. Suspect Ehlers-Danlos syndrome in a young patient who presents with a multitude of the described symptoms or with a ruptured organ or major vessel. Physical examination may show hyperextensible skin (defined as stretching the skin greater than 4 centimeters) and hypermobile joints (defined as dorsiflexing the thumb greater than 90 degrees). Diagnosis is clinical. Many of these patients will suffer from degenerative disk disease as a result of constant joint dislocations. In addition, many will report severe musculoskeletal pain. Because these patients appear healthy, they are frequently misdiagnosed with chronic fatigue or depression. Treatment is supportive and includes patient education, counseling, and lifestyle modifications.
I-cell disease
Inclusion (I) cell disease is an inherited lysosomal storage disorder that results from a failure to add mannose-6-phosphate to lysosome proteins, leading to secretion of these proteins rather than targeted destruction. Signs and symptoms include high plasma levels of lysosomal enzymes, clouded corneas, coarse facial features, and childhood morbidity.
Kartagener's syndrome
Kartagener’s syndrome, or primary ciliary dyskinesia (PCD), results from a dynein arm defect. It can lead to male or female infertility, recurrent sinusitis, and bronchiectasis. It may also be associated with situs inversus.
Menkes disease
Menkes disease is a X-linked recessive condition which manifest itself in newborns. A mutation in the ATP7A protein causes impaired copper transportation across cell membranes. Lysyl oxidase, which uses copper as a cofactor, can no longer properly function. Symptoms include hypotonia and delayed growth.
Question 2.
A 25-year-old woman comes to the clinic because of redness of both eyes of two days’ duration. The symptoms began yesterday and were preceded by an upper respiratory infection. On examination, visual acuity is normal and the conjunctiva are hyperemic bilaterally. There is watery discharge from the eyes. A diagnosis of conjunctivitis is made and she is prescribed symptomatic relief. Which of the following best describes the most likely cause of infection in this patient?
Herpes simplex virus type 1
Herpes simplex virus type 1 causes ocular herpes is a common, recurrent viral infection affecting the eyes. Symptoms include inflammation of the cornea, which can lead to severe and sudden ocular pain. The cornea can also become cloudy, leading to blurry vision.
Complication from contact lenses
Giant papillary conjunctivitis usually involves both eyes and is often caused by contact lens use. It may cause contact lens intolerance, itching, a heavy discharge, tearing, and red bumps on the underside of the eyelids
Streptococcus pneumoniae
Streptococcus pneumoniae is a common cause of bacterial conjunctivitis. When the causative agent for conjunctivitis is a bacteria, the infection will typically involve thick eye discharge or pus. It can affect one or both eyes.
Seasonal allergies
Allergic conjunctivitis is very common and can be caused by pollen, animal dander, and dust mites. It typically presents with itchiness, which may be controlled with antihistamine-containing eye drops.
Adenovirus
Major takeaway
Adenovirus is a common cause of conjunctivitis and upper respiratory infections. In immunosuppressed individuals it can cause life-threatening illnesses. Viral conjunctivitis is airborne and can be spread through sneezing and coughing
Main explanation
Viral conjunctivitis is a common type of pink eye that is highly contagious. It is airborne and can be spread through sneezing and coughing. Viral conjunctivitis may accompany common viral upper respiratory infections such as measles, the flu, or common cold. Typically the infection starts in one eye and spreads to the other eye. Watery discharge is very common with viral conjunctivitis. Adenovirus is a common cause of conjunctivitis and upper respiratory infections. In immunosuppressed individuals it can cause life-threatening illnesses. Proper hygiene including hand-washing is recommended to reduce spread. Adenovirus is a double-stranded DNA virus. Other double-stranded DNA viruses include the herpesviruses, papillomaviruses, and poxviruses.
Question 3.
A nine-month-old boy is brought into the pediatric clinic by his parents for a well-child exam. His family is of Ashkenazi Jewish descent. There is no family history of any genetic disorders, and no prenatal testing was initiated. He was born at term with no developmental anomalies noted during the first six months of life. At the physical examination, the patient is unable to roll over as he was able to do at six months. Abdominal examination is normal. His parents note that he startles easily at loud noises. Neuromuscular examination shows global hypotonia and hyporeflexia. Ophthalmologic examination reveals a red lesion on the maculae of both eyes. Which of the following is the most likely diagnosis?
Bloom syndrome
While Bloom syndrome is associated with Ashkenazi Jewish heritage due to an increased carrier frequency, this disorder is characterized by short stature and a predisposition to cancer.
Down syndrome
Down syndrome presents with delayed developmental milestones, not the loss of previously obtained milestones. A cherry-red spot is not typical.
Gaucher disease
Gaucher disease is characterized by findings of hepatosplenomegaly, thrombocytopenia, and may or may not include neurologicsymptoms. Typically, this condition does not present with a cherry-red spot.
Niemann-Pick disease
Niemann-Pick disease is due to sphingomyelin accumulation. Like Tay-Sachs disease, it causes progressive neurodegeneration and a cherry red spot on the macula can be seen. However, Niemann-Pick disease is characterized by hepatosplenomegaly, ataxia, thrombocytopenia, and dysarthria.
Tay-Sachs disease
Major takeaway
Tay-Sachs disease is a progressive neurodegenerative disease due to a deficiency of the enzyme hexosaminidase A. Prior to one-year-old, it is characterized by loss of developmental milestones, seizures, hypotonia, hyporeflexia, and macrocephaly. There is a characteristic cherry red spot because of accumulation of the glycolipid GM2 ganglioside in the layers of the retina.
Main explanation
This child is of Ashkenazi Jewish descent, and comes to the clinic with a progressive loss of motor reflexes, along with the physical findings of hypotonia (which progresses to hyperreflexia after approximately one year of age), hyporeflexia, and a cherry-red spot. This suggests a progressive neurodegenerative disorder of genetic origin (no prenatal testing was done on this child). One of the most common of these conditions is Tay Sachs disease. Other characteristic findings of Tay-Sachs disease are macrocephaly, seizures, vision loss, and hearing loss. It is inherited in an autosomal recessive fashion, and is due to a defect in the HEXA gene, coding for the hexosaminidase A enzyme. This results in accumulation of the glycolipid GM2 ganglioside both in neurons, causing progressive neurodegeneration, as well as the layers of the retina, concentrated at the macula, resulting in a cherry red spot.
Question 4.
A 22-year-old woman comes to the student health center with pustules on her face, surrounding her nose and lips. The lesions appear honey-crusted, and are not painful. She has noticed no other symptoms, and denies fever, cough, or sore throat. Her past medical history is significant for a broken arm at age 8, but otherwise unremarkable. She is in her final year at college, and lives in a crowded residence hall. When the pustules are cultured, the results are catalase-negative cocci (pictured below). Which of the following sequelae would you be most worried about?
Back and hip pain, fever, and chills
These symptoms suggest osteomyelitis, a dangerous possible sequelae of a Staphylococcus aureus infection. A Staphylococcusculture would reveal catalase-positive gram-positive cocci in clusters, not chains.
Fever, increased heart rate, and the presence of bacteria in the blood
These symptoms suggest septicemia, or bacterial infection of the blood. Though impetigo may spread through the skin and eventually come in contact with the blood, this is an incredibly rare occurrence, and will not occur with effective treatment.
Fever, multiple painful joints, and a non-itchy rash
These symptoms suggest acute rheumatic fever, an important sequelae to look for after pharyngitis caused by group A Streptococcus (GAS). However, there is no correlation between rheumatic fever and skin GAS infection.
Hematuria, edema, and fever
Major takeaway
Acute glomerulonephritis can be caused by both pharyngeal and skin infections with GAS, but only pharyngeal infections typically lead to acute rheumatic fever.
Main explanation
This is the classic presentation of glomerulonephritis, an important sequelae of both GAS pharyngitis and GAS skin infection. Honey crusted lesions are the hallmark of impetigo, a skin infection caused by Streptococcus pyogenes and Staphylococcus aureus. Since the culture was catalase negative, we have ruled out S. aureus. The picture shows gram positive (positive is purple) cocci in chains, the classic depiction of streptococcal species, which helps strengthen our diagnosis. Streptococcus pyogenes is also known as group A Streptococcus (GAS), and is beta-hemolytic. It is the causative agent of streptococcal pharyngitis, more commonly known as strep throat. Acute rheumatic fever, most likely caused by cross-reactivity between the GASM protein and cardiac and joint tissue, is a clinically relevant possible sequelae of streptococcal pharyngitis, though it can be avoided with prompt treatment. Both pharyngeal and skin infection with GAS can lead to acute glomerulonephritis, which is thought to be caused by immune complex deposition in the glomeruli. Meningitis and septicemia are more commonly associated with Streptococcus pneumoniae. Osteomyelitis is an important sequelaeto consider when dealing with a staphylococcal infection, but is not typically associated with streptococcal species.
Stiff neck, fever, and seizures
These symptoms suggest meningitis, and the most common bacterial causes in this age group are Streptococcus pneumoniae or Neisseria meningitidis. Spread of Streptococcus pyogenes infection may spread from the pharynx to the meninges and cause meningitis, but impetigo is not correlated with meningitis.
Question 5.
A 62-year-old man comes to the clinic for a routine yearly examination. He has no acute complaints and says that he has felt well for the past year. However, his father recently passed away from multiple myeloma and he insists that he be tested for it. His medical history is noncontributory. He exercises for one hour each morning and eats a balanced diet. His temperature is 37.0°C (98.6°F), pulse is 81/min, respirations are 12/min, and blood pressure is 136/82 mm Hg. Physical examination shows a well-developed and well-nourished male who appears his stated age. Serum protein electrophoresis shows a small but significant serum monoclonalprotein spike. Complete blood count and complete metabolic panels are both within normal limits. Review of systems is negative for bone pain, fatigue, or urinary symptoms. Which of the following is the most likely diagnosis?
Langerhans cell histiocytosis
Langerhans cell histiocytosis is a neoplastic disorder characterized by the proliferation of these dendritic cells which reside primarily in the skin. On histology, classic Birbeck granules, which are said to be shaped like tennis rackets, can be seen.
Monoclonal gammopathy of undetermined significance
Major takeaway
A monoclonal gammopathy is a disorder characterized by an abundance of a monoclonalimmunoglobulin in the serum of an affected patient.Monoclonal gammopathy of undetermined significance (MGUS), which caused by a monoclonal expansion of plasma cells, is the most common type of monoclonal gammopathy.
Main explanation
A monoclonal gammopathy is a disorder characterized by an abundance of a monoclonalimmunoglobulin in the serum of an affected patient. Depending on the type of immunoglobulin and the presence, or lack thereof, of associated symptoms, the name of the diagnosis varies. In this case, the asymptomatic patient was incidentally found to have this excess protein on routine bloodwork. Monoclonal gammopathy of undetermined significance (MGUS), which caused by a monoclonal expansion of plasma cells, is the most common type of plasma cell dyscrasia. In some patients, the number of monoclonal plasma cells increases sufficiently enough that the disorder progresses to one of several potential malignant diseases, such as multiple myeloma or Waldenstrom macroglobulinemia. Whereas these two malignancies can each present with dangerous clinical symptoms, it is important to routinely monitor a patient with MGUS for increases in serum levels of immunoglobulins that would signify a malignant transformation of the condition.
Multiple myeloma
Multiple myeloma is a cancer of plasma cells characterized by the monoclonal production of large amounts of either IgG or IgA antibodies. As compared to monoclonal gammopathy of undetermined significance, multiple myeloma produces clinical symptoms such as hypercalcemia, anemia, lytic bone lesions, and the kidneys may become involved.
Pseudo-Pelger-Huet anomaly
Pseudo-Pelger-Huet anomaly is a histological finding of bilobed nuclei in neutrophils typically after patients with myelodysplastic syndrome undergo chemotherapy treatment.
Waldenstrom macroglobulinemia
Waldenstrom macroglobulinemia is a plasma cell dyscrasia similar to multiple myeloma, except that the excess serum protein is IgM, rather than IgG or IgA. Its classic symptom is hyperviscosity syndrome characterized by headaches or blurred vision.
Question 6.
A 65-year-old woman comes to the clinic for a routine checkup. She has unintentionally lost 10 lbs in the past month but denies any other complaints. Pulse is 90/min, respirations are 18/min, and blood pressure is 150/70. An irregularly irregular rhythm is heard on auscultation of the heart. Neck examination shows a markedly enlarged thyroid with no lymphadenopathy or bruit. Laboratory tests show low serum thyroid-stimulating hormone, high T4, absent thyroid-stimulating immunoglobulin, and absent anti-thyroid peroxidase antibody. Nuclear scintigraphy shows patchy uptake with multiple hot and cold areas.Which of the following is the most likely diagnosis?
Graves disease
Graves disease is the most common cause of hyperthyroidism, but it is often diagnosed at a younger age (40-60 years). Also, autoimmune features are absent (exophthalmos, positive thyroid-stimulating immunoglobulin).
Hashimoto thyroiditis
Hashimoto (chronic lymphocytic) thyroiditis is an autoimmune disease that attacks the thyroid, causing symptoms of hypothyroidism. Laboratory tests consistent with hypothyroidism and thus Hashimoto thyroiditis include increased serum thyroid-stimulating hormone (TSH) and positive anti-thyroid peroxidase antibody.
Subacute granulomatous thyroiditis
Subacute granulomatous (de Quervain) thyroiditis involves short (<3 month) thyrotoxic and/or hypothyroid phases. It is characterized by anterior neck pain and tenderness.
Toxic adenoma
Toxic adenoma is characterized by a single, large, palpable nodule. Patients with toxic adenoma tend to be younger (30- 50 years).
Toxic multinodular goiter
Major takeaway
Toxic multinodular goiter is characterized by an enlarged thyroid due to multiple autonomous nodules – some with normal, decreased, elevated (toxic) function.
Main explanation
Hyperthyroidism causes symptoms such as tachycardia, palpitations, diarrhea, weight loss, and heat intolerance. Three key causes of hyperthyroidism are Graves disease (autoimmune), toxic adenoma (solitary large nodule), and toxic multinodular goiter. Autoimmune etiology is ruled out by low levels of thyroid-stimulating immunoglobulin (TSI) and/or anti-thyroid peroxidase (anti-TPO) antibody. Goiter is defined as an enlarged thyroid. It can be simple, where the entire thyroid is enlarged, or multinodular. Nodules are toxic when they cause hyperthyroidism. Diagnosis includes ruling out autoimmune etiology with low levels of thyroid-stimulating immunoglobulin (TSI) and/or anti-thyroid peroxidase (anti-TPO) antibody, confirming hyperthyroid with low thyroid-stimulating hormone (TSH) and/or high serum T3 or T4 levels, and imaging with multiple nodules.
Treatment is determined by patient symptoms and overall health and guidelines are constantly evolving. The three major options are pharmacotherapy, radioiodine ablation, and surgical removal. Beta-blockers are provided to most patients for symptom relief and cardiac protection against arrhythmias. First-line pharmacotherapy is methimazole to suppress thyroidproduction. Radioactive iodine functionally shrinks the thyroid by poisoning it, often leading to hypothyroidism as an adverse effect which can be managed with levothyroxine.
Question 7.
A 35-year-old right-handed male construction worker comes to the clinic because of right elbow pain. He rates the pain as a 4 on a 10-point scale, worse at the end of the day, and better with rest. His temperature is 37.3°C (99.1°F), pulse is 72/min, respirations are 16/min, and blood pressure is 126/80. Physical examination shows 5/5 muscle strength bilaterally, 2+ radial and ulnar pulses, and intact sensation throughout the right upper extremity. Increased pain at the lateral aspect of his elbow is produced with resisted wrist extension. A plain radiograph of the elbow is normal. Which of the following is the most likely diagnosis?
Cubital tunnel syndrome
Cubital tunnel syndrome is due to compression of the ulnar nerve as it passes under the flexor carpi ulnaris aponeurosis (Osborns ligament) in the elbow. Cubital tunnel syndrome is characterized by elbow pain but predominately is characterized by paresthesiasin the ulnar nerve distribution.
Elbow osteoarthritis
Elbow osteoarthritis is characterized by elbow pain exacerbated with muscle strength testing and is more common in older patients. Osteoarthritis of the elbow would show degenerative changes on radiographs such as osteophyte formation, joint space narrowing and bony sclerosis.
Lateral epicondylitis
Major takeaway
Lateral epicondylitis, also known as “tennis elbow,” is an overuse injury involving the wrist extensor muscles. The patient is characterized by elbow pain that is made worse with wrist extension and pain to palpation. Treatment begins conservatively with rest, ice, and physical therapy.
Main explanation
Lateral epicondylitis is a common overuse syndrome involving the wrist extensor muscles that attach at or near the lateral epicondyle of the humerus. The usual presentation is lateral elbowpain exacerbated with resisted wrist extension and tenderness to palpation near the lateral epicondyle. Lateral epicondylitis is a common condition affecting laborers and tennis players and is commonly called “tennis elbow.” Conservative treatment is the mainstay and consists of rest, ice, compression elbow straps and physical therapy. When conservative treatments fails, corticosteroid injections are the next most appropriate step in management. If conservative treatment and corticosteroid injections fail to resolve the inflammation, surgical debridement is indicated.
Medial epicondylitis
Medial epicondylitis (“golf elbow”) involves the wrist flexors and is characterized by medial elbow pain that is exacerbated with resisted wrist flexion. Treatment and management are similar to lateral epicondylitis.
Olecranon bursitis
Olecranon bursitis, commonly called “student’s elbow” can be infectious or traumatic in origin. It is due to inflammation of the olecranon bursa posterior to the olecranon and is characterized by posterior elbow pain and may be characterized by classic signs of inflammation such as redness, edema, and heat.
Question 8.
A 61-year-old woman comes to the clinic because of difficulty repeating words and phrases for the past 2 weeks. She is able to comprehend words and sentences with a simple syntactic structure, but she is unable to form fluent speech. The patient also has severe difficulty when she is asked to name objects. Her past medical history is significant for hypertension, diabetes mellitus type 2, and dyslipidemia. Her temperature is 37.8°C (100°F), pulse is 72/min, respirations are 21/min, and blood pressure is 145/90 mm Hg. Physical examination shows no signs of head trauma and an irregular rhythm is heard on auscultation. Which of the following is the most likely diagnosis?
Receptive aphasia
Receptive aphasia is caused by a lesion in the posterior portion of the left hemisphere. Comprehension is poor and the person often produces jargon, or nonsensical words and phrases when attempting to speak. These utterances retain sentence structure but lack meaning.
Expressive aphasia
Major takeaway
Expressive aphasia is characterized by the loss of the ability to produce language (spoken or written). Comprehension is mildly to moderately impaired in expressive aphasia.
Main explanation
Expressive aphasia (non-fluent aphasia, also known as Broca’s aphasia) is characterized by the loss of the ability to produce language (spoken or written). A person with expressive aphasiawill exhibit effortful speech. Speech only include important content words and leave out insignificant words. This is known as “telegraphic speech”. The person can be understood, but sentences are not grammatical. In very severe forms of expressive aphasia a person speaks by only using single word utterances. It is one subset of a larger family of disorders known collectively as aphasia. Comprehension is mildly to moderately impaired in expressive aphasia. This contrasts with receptive aphasia, which is distinguished by a patient’s inability to comprehend language or speak with appropriately meaningful words.
Global aphasia
Global aphasia is a severe impairment of both expressive and receptive skills. It is caused by a large left hemisphere lesion. People are often alert and are able to express themselves through facial expressions, intonation, and gestures.
Conductive aphasia
Conductive aphasia is characterized by prominent impairment with repetition. Damage typically involves the arcuate fasciculus and the left parietal region. The patient is able to express him- or herself fairly well, with some word-finding issues, and comprehension can be functional.
Anomic aphasia
Anomic aphasia is a mild form of aphasia. The most prominent difficulty is in word-finding, with the person using generic fillers in utterances, such as nonspecific nouns and pronouns, or circumlocution, where the person describes the intended word. Comprehension and repetition of words, and sentences is typically good.
Question 9.
A 20-year-old woman comes to the clinic because of vaginal discharge for five days. She is sexually active, and not using any contraceptive. Pelvic examination shows normal external genitalia. There is a moderate amount of malodorous, thin, gray discharge coating the vaginal walls. The vulva and cervix appear normal. There is no cervical motion tenderness on bimanual examination. The pH of the vaginal fluid is 5.0. A wet mount preparation of the vaginal fluid reveals epithelial cells covered with bacteria. A urine pregnancy test is negative. Which of the following is the most appropriate pharmacologic treatment?
Azithromycin
Oral azithromycin and doxycycline are used to treat Chlamydia, which may be asymptomatic or result in mucopurulent vaginaldischarge, adnexal tenderness,lower abdominal tenderness, or cervical motion tenderness. The presence of thin gray discharge, clue cells, and elevated vaginal pH make bacterial vaginosis a more likely diagnosis.
Doxycycline
Oral azithromycin and doxycycline are used to treat Chlamydia, which may be asymptomatic or result in mucopurulent vaginaldischarge, adnexal tenderness,lower abdominal tenderness, or cervical motion tenderness. The presence of thin gray discharge, clue cells, and elevated vaginal pH make bacterial vaginosis a more likely diagnosis.
Metronidazole
Major takeaway
Bacterial vaginosis is diagnosed most commonly utilizing office based microscopy which reveals clue cells. Treatment is accomplished with metronidazole. Vaginal clindamycin can also be used.
Main explanation
This patient’s presentation is consistent with a diagnosis of bacterial vaginosis caused by Gardnerella vaginalis. Clinical diagnosis of bacterial vaginosis can be made by demonstrating at least 3 of the following 4 Amsel criteria:
1. Vaginal fluid demonstrates the presence of clue cells on wet mount microscopy. Clue cellsare vaginal epithelial cells with adherent bacteria,giving them a “fuzzy” appearance on microscopy.
2. Vaginal discharge with a pH of >4.5.
3. The discharge is homogenous. Though this is characteristically white or gray discharge, the color and amount is variable.
4. Positive whiff test. When a drop of 10% potassium hydroxide is placed on a sample of the vaginal fluid, a fishy odor results from the release of volatile amines from the fluid.
Bacterial vaginosis can be treated with oral or vaginal metronidazole. Vaginal clindamycin can also be used.
Ceftriaxone
Intramuscular ceftriaxone is used to treat gonorrhea, which may be asymptomatic or present with mucopurulent vaginal discharge or post-coital vaginal bleeding. Gram stain shows gram-negative diplocci.
Miconazole
Vulvovaginal candidiasis is treated with vaginal miconazole. Symptoms of vulvovaginal candidiasis include vulvar itching or irritation, clumped, white discharge, and vulvar erythema or tenderness. The pH of the vaginal fluid is usually <4.5. Potassium hydroxide preparation may reveal budding filaments or pseudohyphae on microscopic exam.
Question 10.
A 34-year-old woman, gravida 2, para 1 at 28 weeks’ gestation presents to the clinic for routine antepartum surveillance. She explains that recently, she has not felt her baby move as much as she has in the past. She complains of fatigue and joint pain. Ultrasound shows accumulation of fluid in the subcutaneous tissue and abdomen. Fetal Doppler assessment shows severe anemia. Amniocentesis shows fetal infection with parvovirus B19. Which of the following is the most likely diagnosis?
Amniotic band sequence
In amniotic band sequence, loose strings of amnion adhere to and wrap around the fetus, resulting in mechanical or vascular disruption of developing structures. Clinical manifestations include limb and digital amputation and craniofacial abnormalities.
Holoprosencephaly
Holoprosencephaly results from incomplete development and septation of the midline central nervous system structures. Severe cases are associated with a proboscis, cyclopia, midfacial clefting, and hydrocephalus.
Hydrops fetalis
Major takeaway
Hydrops fetalis is a condition characterized by the accumulation of fluid in at least two fetal compartments. It commonly manifests as fluid in the subcutaneous tissue, Pericardium, pleura, and peritoneum. Common causes are maternal syphilis, alpha thalassemia major, and parvovirus B19 infection.
Main explanation
Hydrops fetalis is Latin for “edema of the fetus.” It is a condition characterized by the accumulation of fluid in at least two fetal compartments. It commonly manifests as fluid in the subcutaneous tissue, but it can also cause pericardial or pleural effusion and ascites. It is due to an imbalance in fluid homeostasis, with more fluid accumulating than can be resorbed. It usually stems from fetal anemia, and this anemia can have either an immune or non-immune cause. Rh disease, or hemolytic disease of the newborn, is the main cause of immune-mediated hydrops fetalis. There are many causes of non-immune mediated hydrops fetalis, but the more common causes are maternal syphilis, alpha thalassemia major, and parvovirus B19infection. This disease is diagnosed and monitored using ultrasound. Mortality rate is very high; however, fetuses with this disease can now be treated with blood transfusion while in the womb, which increases the likelihood that the fetus will survive until birth.
Oligohydramnios
Oligohydramnios is a condition characterized by a low amount of amniotic fluid. An adequate volume is critical to allow normal fetal movement and growth. Oligohydramnios may inhibit these processes and can lead to fetal deformation, umbilical cordcompression, and death. The opposite, polyhydramnios, can cause hydrops fetalis.
Potter syndrome
This syndrome is characterized by pulmonary hypoplasia, limb deformations, and flattened facies. It results from external compression of the fetus, limitation of fetal movement, and alteration in lung liquid movement due to severe oligohydramnios. It occurs secondary to renal agenesis.
