A 34-year-old woman comes to the physician because of a 3-month history of fatigue and a 4.5-kg (10-lb) weight loss despite eating more than usual. Her pulse is 115/min and blood pressure is 140/60 mm Hg. Physical examination shows warm, moist skin, and a diffuse, non-tender swelling over the anterior neck. Ophthalmologic examination shows swelling of the eyelids and proptosis bilaterally. Which of the following is the most likely cause of this patient's symptoms?
Q2
A 32-year-old woman presents with a 3-month history of intermittent blurred vision and problems walking. The patient states that she often feels “pins and needles” in her legs that cause her problems when she’s walking. The patient is afebrile, and her vital signs are within normal limits. An autoimmune disorder is suspected. Which of the following findings would most likely be present in this patient?
Q3
A 43-year-old woman presents to the physician with the complaint of worsening fatigue over the past several months. She has found that she requires nearly double the amount of coffee consumption each day to stay awake at work and that despite maintaining a balanced, healthy diet, she has experienced significant weight gain. A blood test confirms the presence of anti-thyroid peroxidase antibodies. Which of the following additional findings would be most consistent with the underlying pathophysiology of her condition?
Q4
A 21-year-old female presents to her obstetrician because she has stopped getting her period, after being irregular for the last 3 months. Upon further questioning, the patient reveals that she has had a 17 lb. unintended weight loss, endorses chronic diarrhea, abdominal pain, and constipation that waxes and wanes. Family history is notable only for an older brother with Type 1 Diabetes. She is healthy, and is eager to gain back some weight. Her OBGYN refers her to a gastroenterologist, but first sends serology laboratory studies for IgA anti-tissue transglutaminase antibodies (IgA-tTG). These results come back positive at > 10x the upper limit of normal. Which of the following is the gastroenterologist likely to find on endoscopy and duodenal biopsy?
Q5
A 35-year-old man presents with large tense blisters on the flexor surfaces of the upper extremities and trunk. The histologic findings show subepidermal blisters with an eosinophil-rich infiltrate. What is the most likely underlying pathology?
Q6
A 35-year-old woman comes to the physician because of a 1-month history of double vision, difficulty climbing stairs, and weakness when trying to brush her hair. She reports that these symptoms are worse after she exercises and disappear after she rests for a few hours. Physical examination shows drooping of her right upper eyelid that worsens when the patient is asked to gaze at the ceiling for 2 minutes. There is diminished motor strength in the upper extremities. The remainder of the examination shows no abnormalities. Which of the following is the most likely diagnosis?
Q7
A 58-year-old woman presents with tense bullae on an erythematous base, primarily affecting her trunk and extremities. The lesions developed over the past 3 weeks. Nikolsky sign is negative. Skin biopsy shows subepidermal bullae with eosinophilic infiltrate. Direct immunofluorescence shows linear deposits of IgG and C3 at the basement membrane zone. Which of the following is the target antigen in this condition?
Q8
A 47-year-old woman presents to her physician for difficulty swallowing. She states that she intentionally delayed seeing a physician for this issue. She says her primary issue with swallowing is that her mouth always feels dry so she has difficulty chewing food to the point that it can be swallowed. On physical examination, her oral mucosa appears dry. Both of her eyes also appear dry. Several enlarged lymph nodes are palpated. Which of the following patterns of reactive lymphadenitis is most commonly associated with this patient’s presentation?
Q9
A 51-year-old woman with hyperlipidemia comes to the physician because of weakness for one month. At the end of the day, she feels too fatigued to cook dinner or carry a laundry basket up the stairs. She also complains of double vision after she reads for long periods of time. All of her symptoms improve with rest. Her only medication is pravastatin. Physical examination shows drooping of the upper eyelids. Strength is initially 5/5 in the upper and lower extremities but decreases to 4/5 after a few minutes of sustained resistance. Sensation to light touch is intact and deep tendon reflexes are normal. Which of the following best describes the pathogenesis of this patient's condition?
Q10
A 72-year-old nursing home resident is complaining of pruritis. She is noted to have multiple, tense blisters on her trunk as well as the flexor surfaces of her extremities. The blisters have an erythematous base. You are unable to extend the blisters when you apply lateral traction. You suspect an autoimmune bullous dermatosis. Which of the following is the cause of the likely condition?
Organ-specific autoimmune diseases US Medical PG Practice Questions and MCQs
Question 1: A 34-year-old woman comes to the physician because of a 3-month history of fatigue and a 4.5-kg (10-lb) weight loss despite eating more than usual. Her pulse is 115/min and blood pressure is 140/60 mm Hg. Physical examination shows warm, moist skin, and a diffuse, non-tender swelling over the anterior neck. Ophthalmologic examination shows swelling of the eyelids and proptosis bilaterally. Which of the following is the most likely cause of this patient's symptoms?
A. Constitutively active TSH receptor
B. Thyrotropin receptor autoantibodies (Correct Answer)
C. Parafollicular cell hyperplasia
D. Thyroid peroxidase autoantibodies
E. Nongranulomatous thyroid inflammation
Explanation: ***Thyrotropin receptor autoantibodies***
* The patient presents with symptoms of **hyperthyroidism** (fatigue, weight loss despite increased appetite, tachycardia, warm moist skin, diffuse goiter) along with **exophthalmos** (proptosis) and **eyelid swelling**.
* These clinical features are classic for **Graves' disease**, which is caused by antibodies stimulating the **TSH receptor** on thyroid follicular cells, leading to excessive thyroid hormone production.
*Constitutively active TSH receptor*
* While a constitutively active TSH receptor can lead to hyperthyroidism, it typically occurs in conditions like **toxic multinodular goiter** or **toxic adenoma**, or rarely, in a **hereditary form** of hyperthyroidism.
* It does **not explain the exophthalmos and eyelid swelling**, which are characteristic autoimmune manifestations of Graves' disease.
*Parafollicular cell hyperplasia*
* **Parafollicular cells** (C cells) produce calcitonin, and their hyperplasia is associated with **medullary thyroid carcinoma**.
* This condition primarily affects calcium metabolism and does **not cause hyperthyroidism or exophthalmos**.
*Thyroid peroxidase autoantibodies*
* **Thyroid peroxidase (TPO) antibodies** are characteristic of autoimmune thyroid diseases but are most strongly associated with **Hashimoto's thyroiditis**, which typically causes **hypothyroidism**.
* While TPO antibodies can be present in Graves' disease, the primary pathology driving the hyperthyroidism and ophthalmopathy is the **TSH receptor antibody**.
*Nongranulomatous thyroid inflammation*
* **Nongranulomatous inflammation** can occur in various thyroid conditions, including subacute thyroiditis (de Quervain's thyroiditis) or silent thyroiditis.
* These conditions usually present with a **transient phase of hyperthyroidism** followed by hypothyroidism, and they typically **do not cause ophthalmopathy or a diffuse, non-tender goiter** as seen here.
Question 2: A 32-year-old woman presents with a 3-month history of intermittent blurred vision and problems walking. The patient states that she often feels “pins and needles” in her legs that cause her problems when she’s walking. The patient is afebrile, and her vital signs are within normal limits. An autoimmune disorder is suspected. Which of the following findings would most likely be present in this patient?
A. Damaged myelin sheath and myelin-producing cells (Correct Answer)
B. Absence of interneurons
C. Destruction of blood-brain barrier
D. Degeneration of anterior horn cells
E. Decreased cerebrospinal fluid due to destruction of cells
Explanation: ***Damaged myelin sheath and myelin-producing cells***
- The patient's symptoms of intermittent **blurred vision** (optic neuritis), **problems walking** (ataxia, spasticity), and **paresthesias** ("pins and needles") are classical presentations of Multiple Sclerosis (MS).
- MS is characterized by multifocal areas of inflammation and **demyelination** in the central nervous system, where the **myelin sheath** surrounding axons is damaged, and the **oligodendrocytes** (myelin-producing cells) are attacked.
- This demyelination disrupts saltatory conduction, leading to the varied and intermittent neurological symptoms.
*Absence of interneurons*
- The absence of **interneurons** is typically associated with conditions like **spinal muscular atrophy** or certain **neuropathies**, which present with different clinical features (e.g., muscle weakness, atrophy) than those described.
- While interneurons are crucial for neuronal communication, their absence doesn't explain the *intermittent* and multifocal symptoms seen in this case.
*Destruction of blood-brain barrier*
- While **blood-brain barrier (BBB) breakdown** does occur in MS, it is a *consequence* of the inflammatory process rather than the primary *pathological finding* that directly explains the neurological symptoms.
- BBB destruction allows inflammatory cells to enter the CNS, contributing to demyelination, but the core issue remains the myelin damage itself.
*Degeneration of anterior horn cells*
- **Anterior horn cell degeneration** is the hallmark of **amyotrophic lateral sclerosis (ALS)** and **spinal muscular atrophy**, presenting with progressive muscle weakness, atrophy, and fasciculations.
- These conditions lack the sensory symptoms (paresthesias) and visual disturbances seen in this patient, and typically show a progressive rather than intermittent course.
*Decreased cerebrospinal fluid due to destruction of cells*
- **Decreased CSF volume** is not a characteristic feature of MS; in fact, CSF analysis often shows increased protein and **oligoclonal bands**.
- The destruction of cells in MS primarily affects myelin and oligodendrocytes, not cells responsible for CSF production or volume regulation.
Question 3: A 43-year-old woman presents to the physician with the complaint of worsening fatigue over the past several months. She has found that she requires nearly double the amount of coffee consumption each day to stay awake at work and that despite maintaining a balanced, healthy diet, she has experienced significant weight gain. A blood test confirms the presence of anti-thyroid peroxidase antibodies. Which of the following additional findings would be most consistent with the underlying pathophysiology of her condition?
A. Galactorrhea (Correct Answer)
B. Constipation
C. Brisk deep tendon reflexes
D. Diarrhea
E. Heat intolerance
Explanation: ***Galactorrhea***
- This patient has **Hashimoto's thyroiditis**, an autoimmune hypothyroidism, given the fatigue, weight gain, and positive **anti-thyroid peroxidase antibodies**.
- **Hypothyroidism** can lead to **hyperprolactinemia** due to increased **TRH** (thyrotropin-releasing hormone), which stimulates both TSH and prolactin release from the anterior pituitary.
- Elevated prolactin can manifest as **galactorrhea**, representing a less commonly recognized endocrine consequence of primary hypothyroidism.
*Constipation*
- **Constipation** is a common symptom of **hypothyroidism** due to decreased gastrointestinal motility.
- While consistent with hypothyroidism, it is a direct consequence of reduced metabolic activity rather than a secondary endocrine effect.
- This is a well-known, expected finding rather than an additional pathophysiologic manifestation.
*Brisk deep tendon reflexes*
- **Hypothyroidism** typically causes **delayed relaxation of deep tendon reflexes** (hung-up reflexes), not brisk reflexes.
- **Brisk reflexes** are characteristic of **hyperthyroidism** due to increased neuromuscular excitability.
*Diarrhea*
- **Diarrhea** is typically associated with **hyperthyroidism** due to increased gastrointestinal motility from elevated metabolic rate.
- **Hypothyroidism** more commonly causes **constipation** due to decreased GI motility.
*Heat intolerance*
- **Heat intolerance** is a classic symptom of **hyperthyroidism** due to an elevated metabolic rate and increased thermogenesis.
- Patients with **hypothyroidism** usually experience **cold intolerance** due to decreased metabolic heat production.
Question 4: A 21-year-old female presents to her obstetrician because she has stopped getting her period, after being irregular for the last 3 months. Upon further questioning, the patient reveals that she has had a 17 lb. unintended weight loss, endorses chronic diarrhea, abdominal pain, and constipation that waxes and wanes. Family history is notable only for an older brother with Type 1 Diabetes. She is healthy, and is eager to gain back some weight. Her OBGYN refers her to a gastroenterologist, but first sends serology laboratory studies for IgA anti-tissue transglutaminase antibodies (IgA-tTG). These results come back positive at > 10x the upper limit of normal. Which of the following is the gastroenterologist likely to find on endoscopy and duodenal biopsy?
A. Friable mucosal pseudopolyps with biopsy notable for crypt abscesses
B. Cobblestoning with biopsy showing transmural inflammation and noncaseating granulomas
C. Villous atrophy with crypt lengthening and intraepithelial lymphocytes (Correct Answer)
D. Foamy macrophages, which stain PAS positive
E. Normal appearing villi and biopsy
Explanation: ***Villous atrophy with crypt lengthening and intraepithelial lymphocytes***
- The patient's symptoms (amenorrhea, weight loss, diarrhea, abdominal pain, constipation) combined with a **positive IgA anti-tissue transglutaminase antibody (IgA-tTG)** strongly suggest **celiac disease**.
- The characteristic endoscopic and histological findings in celiac disease are **villous atrophy**, **crypt hyperplasia (lengthening)**, and increased **intraepithelial lymphocytes** in the small intestine.
*Friable mucosal pseudopolyps with biopsy notable for crypt abscesses*
- This description is characteristic of **ulcerative colitis**, an inflammatory bowel disease, which typically causes **bloody diarrhea** and is not associated with positive IgA-tTG antibodies.
- **Pseudopolyps** result from cycles of ulceration and regeneration, and **crypt abscesses** are hallmarks of active inflammation in ulcerative colitis.
*Cobblestoning with biopsy showing transmural inflammation and noncaseating granulomas*
- This describes the typical findings in **Crohn's disease**, another inflammatory bowel disease, which can cause **abdominal pain** and **diarrhea** but is not linked to IgA-tTG antibodies.
- **Transmural inflammation** means inflammation extends through all layers of the bowel wall, and **noncaseating granulomas** are a key distinguishing feature.
*Foamy macrophages, which stain PAS positive*
- These findings are characteristic of **Whipple's disease**, a rare bacterial infection caused by *Tropheryma whipplei*.
- While Whipple's disease can present with **malabsorption** and **weight loss**, it is not associated with positive celiac serology.
*Normal appearing villi and biopsy*
- Given the patient's strong clinical suspicion for celiac disease and a **highly positive IgA-tTG** test, normal findings on endoscopy and biopsy would be highly unlikely.
- A definitive diagnosis of celiac disease typically requires characteristic histological changes to confirm the serological findings.
Question 5: A 35-year-old man presents with large tense blisters on the flexor surfaces of the upper extremities and trunk. The histologic findings show subepidermal blisters with an eosinophil-rich infiltrate. What is the most likely underlying pathology?
A. Linear band of IgA in the basement membrane
B. Autoantibodies to desmoglein 3
C. Autoantibodies to desmoglein 1
D. Linear band of immunoglobulin G (IgG) in the epidermal basement membrane (Correct Answer)
E. Granular deposits of immunoglobulin A (IgA) in the dermal papilla
Explanation: ***Linear band of immunoglobulin G (IgG) in the epidermal basement membrane***
- This finding, specifically targeting **hemidesmosomes** in the **dermal-epidermal junction**, is characteristic of **bullous pemphigoid**.
- The clinical presentation of **large, tense blisters** on flexor surfaces and the histological finding of **subepidermal blisters** with an **eosinophil-rich infiltrate** are classic for bullous pemphigoid.
*Linear band of IgA in the basement membrane*
- This describes **linear IgA bullous dermatosis**, which typically presents with an **annular or rosette-like pattern of blisters** and is less common than bullous pemphigoid.
- While it also involves subepidermal blistering, the immune reactant is IgA, not IgG, and the morphology of the lesions is often distinct.
*Autoantibodies to desmoglein 3*
- **Autoantibodies to desmoglein 3** are characteristic of **pemphigus vulgaris**, which typically presents with **flaccid blisters** and **mucosal involvement**.
- Histologically, pemphigus vulgaris shows **intraepidermal blistering** (acantholysis), not subepidermal.
*Autoantibodies to desmoglein 1*
- **Autoantibodies to desmoglein 1** are primarily associated with **pemphigus foliaceus** (superficial form) or sometimes **pemphigus vulgaris**, particularly when combined with desmoglein 3 antibodies.
- Pemphigus foliaceus presents with **superficial erosions and crusts**, not large tense blisters, and it is also an intraepidermal blistering disease.
*Granular deposits of immunoglobulin A (IgA) in the dermal papilla*
- This finding is pathognomonic for **dermatitis herpetiformis**, an intensely pruritic condition characterized by **grouped vesicles and urticarial plaques**, often on extensor surfaces.
- The blisters in dermatitis herpetiformis are typically small, not large and tense, and the immune mechanism involves IgA interacting with transglutaminase.
Question 6: A 35-year-old woman comes to the physician because of a 1-month history of double vision, difficulty climbing stairs, and weakness when trying to brush her hair. She reports that these symptoms are worse after she exercises and disappear after she rests for a few hours. Physical examination shows drooping of her right upper eyelid that worsens when the patient is asked to gaze at the ceiling for 2 minutes. There is diminished motor strength in the upper extremities. The remainder of the examination shows no abnormalities. Which of the following is the most likely diagnosis?
A. Amyotrophic lateral sclerosis
B. Myasthenia gravis (Correct Answer)
C. Polymyositis
D. Guillain-Barré syndrome
E. Multiple sclerosis
Explanation: ***Myasthenia gravis***
- The patient's symptoms of **double vision (diplopia)**, **difficulty climbing stairs**, **weakness exacerbated by activity**, and **ptosis (drooping eyelid)** are classic presentations of myasthenia gravis, a disorder of the **neuromuscular junction**.
- The improvement of symptoms after rest and worsening after activity (**fatigability**) is a hallmark feature, as is the positive **Cogan's lid twitch sign** (worsening ptosis on sustained upward gaze).
*Amyotrophic lateral sclerosis*
- This is a disease of both **upper and lower motor neurons**, leading to progressive muscle weakness, atrophy, and spasticity.
- ALS typically does not present with fluctuating weakness or ocular symptoms like **diplopia and ptosis**, and sensory function is usually spared.
*Polymyositis*
- Polymyositis is an **inflammatory myopathy** characterized by **proximal muscle weakness** (e.g., difficulty climbing stairs, brushing hair) that is typically progressive and constant, not fluctuating with activity and rest.
- It does not involve ocular muscles or present with **fatigability** of symptoms.
*Guillain-Barré syndrome*
- This is an **acute demyelinating polyradiculoneuropathy** characterized by **ascending paralysis**, often following an infection.
- Symptoms are usually rapid in onset and progressive, not fluctuating or limited primarily to specific muscle groups that worsen with exertion.
*Multiple sclerosis*
- MS is a **demyelinating disease** of the central nervous system, which can cause varied neurological symptoms depending on the location of lesions.
- While it can cause **diplopia** and **fatigue**, the characteristic fluctuating weakness that improves with rest and specific ocular motor findings like **ptosis** that worsen with sustained gaze are not typical primary features of MS.
Question 7: A 58-year-old woman presents with tense bullae on an erythematous base, primarily affecting her trunk and extremities. The lesions developed over the past 3 weeks. Nikolsky sign is negative. Skin biopsy shows subepidermal bullae with eosinophilic infiltrate. Direct immunofluorescence shows linear deposits of IgG and C3 at the basement membrane zone. Which of the following is the target antigen in this condition?
A. Type IV collagen
B. BP180/BP230 (Correct Answer)
C. Type VII collagen
D. Desmoglein-3
Explanation: ***BP180/BP230***
- The clinical presentation of **tense bullae**, negative **Nikolsky sign**, subepidermal bullae with **eosinophilic infiltrate**, and **linear IgG and C3 deposition at the basement membrane zone** are classic features of **bullous pemphigoid**.
- **BP180** (also known as type XVII collagen) and **BP230** are hemidesmosomal proteins that serve as the primary target antigens in bullous pemphigoid.
*Type IV collagen*
- **Type IV collagen** is a major component of the **basement membrane**, but it is not the target antigen in bullous pemphigoid.
- Antibodies against type IV collagen may be involved in **Goodpasture syndrome**, which affects the kidneys and lungs, not primarily the skin in this manner.
*Type VII collagen*
- **Type VII collagen** is found in the **anchoring fibrils** beneath the basement membrane.
- Antibodies against **type VII collagen** are characteristic of **epidermolysis bullosa acquisita**, which typically presents with **fragile skin, trauma-induced blistering**, and scarring, differentiating it from this case.
*Desmoglein-3*
- **Desmoglein-3** is a **desmosomal protein** that is a primary target antigen in **pemphigus vulgaris**, especially the **mucosal dominant form**.
- **Pemphigus vulgaris** is characterized by **flaccid bullae, painful erosions**, and a **positive Nikolsky sign**, which are not consistent with the patient's presentation.
Question 8: A 47-year-old woman presents to her physician for difficulty swallowing. She states that she intentionally delayed seeing a physician for this issue. She says her primary issue with swallowing is that her mouth always feels dry so she has difficulty chewing food to the point that it can be swallowed. On physical examination, her oral mucosa appears dry. Both of her eyes also appear dry. Several enlarged lymph nodes are palpated. Which of the following patterns of reactive lymphadenitis is most commonly associated with this patient’s presentation?
A. Sinus hyperplasia
B. Follicular hyperplasia (Correct Answer)
C. Diffuse hyperplasia
D. Mixed B and T cell hyperplasia
E. Paracortical hyperplasia
Explanation: ***Follicular hyperplasia***
- The patient's symptoms of **dry mouth (xerostomia)** and **dry eyes (xerophthalmia)** strongly suggest **Sjögren syndrome**. This autoimmune disease selectively affects **exocrine glands**, particularly the salivary and lacrimal glands.
- Lymphoid hyperplasia, especially **follicular hyperplasia**, is a common feature in Sjögren syndrome due to chronic B-cell activation, which is linked to a higher risk of developing **MALT lymphoma**.
*Sinus hyperplasia*
- **Sinus hyperplasia**, also known as **reticular hyperplasia**, is characterized by an increase in the number and size of macrophages within the subcapsular and medullary sinuses of lymph nodes.
- It is typically associated with **lymph nodes draining a site of malignancy** or conditions involving histiocytic proliferation.
*Diffuse hyperplasia*
- **Diffuse hyperplasia** involves a generalized expansion of all lymphoid components within the lymph node, without a predominance of any specific area.
- This pattern is less specific and can be seen in various **chronic inflammatory conditions** or reactive processes, but it is not the most characteristic pattern for Sjögren syndrome.
*Mixed B and T cell hyperplasia*
- While both B and T cells are involved in immune responses, **mixed B and T cell hyperplasia** refers to the expansion of both populations in a less defined pattern than follicular or paracortical types.
- Conditions like **toxoplasmosis** can present with mixed hyperplasia, but it is not the classic pattern seen in Sjögren syndrome.
*Paracortical hyperplasia*
- **Paracortical hyperplasia** involves the expansion of the paracortical areas of the lymph node, which are rich in T-lymphocytes.
- This pattern is typically seen in response to **viral infections** (e.g., infectious mononucleosis) or certain drug reactions, where T-cell activation is a prominent feature.
Question 9: A 51-year-old woman with hyperlipidemia comes to the physician because of weakness for one month. At the end of the day, she feels too fatigued to cook dinner or carry a laundry basket up the stairs. She also complains of double vision after she reads for long periods of time. All of her symptoms improve with rest. Her only medication is pravastatin. Physical examination shows drooping of the upper eyelids. Strength is initially 5/5 in the upper and lower extremities but decreases to 4/5 after a few minutes of sustained resistance. Sensation to light touch is intact and deep tendon reflexes are normal. Which of the following best describes the pathogenesis of this patient's condition?
A. Type II hypersensitivity reaction (Correct Answer)
B. Anterior horn cell destruction
C. Impaired acetylcholine release
D. Peripheral nerve demyelination
E. Adverse drug effect
Explanation: ***Type II hypersensitivity reaction***
- This patient's symptoms of **fatigue** and **muscle weakness** that worsen with activity and improve with rest (**fatigable weakness**), along with **ptosis** (drooping eyelids) and **diplopia** (double vision), are classic for **myasthenia gravis**.
- Myasthenia gravis is an **autoimmune disease** characterized by autoantibodies that target and destroy **acetylcholine receptors** at the neuromuscular junction, leading to impaired signal transmission. This is a classic example of a **Type II hypersensitivity reaction**, where antibodies directly mediate cellular destruction or dysfunction.
*Anterior horn cell destruction*
- **Anterior horn cell destruction**, as seen in **amyotrophic lateral sclerosis (ALS)**, typically presents with both upper and lower motor neuron signs, such as **spasticity**, **hyperreflexia**, **fasciculations**, and **muscle atrophy**.
- In ALS, there is progressive weakness but typically **without fatigability** and oculomotor symptoms (ptosis, diplopia) are less common or occur late in the disease.
*Impaired acetylcholine release*
- **Impaired acetylcholine release** is characteristic of **Lambert-Eaton myasthenic syndrome (LEMS)**, which is often associated with small cell lung cancer.
- Unlike myasthenia gravis, LEMS typically shows **improvement in muscle strength with sustained activity** (due to increased presynaptic acetylcholine release), rather than worsening.
*Peripheral nerve demyelination*
- **Peripheral nerve demyelination** is the hallmark of conditions like **Guillain-Barré syndrome (GBS)** or **chronic inflammatory demyelinating polyneuropathy (CIDP)**.
- These conditions usually present with **sensory deficits**, **areflexia**, and **ascending paralysis/weakness**, which are absent in this patient.
*Adverse drug effect*
- While **statins** can cause **myopathy** (muscle pain and weakness), this typically involves diffuse muscle aches and elevated **creatine kinase** levels, and does not typically present with the classic fatigable weakness, ptosis, and diplopia seen here.
- The specific pattern of fatigable weakness improving with rest and affecting specific muscle groups (e.g., ocular muscles) points away from a simple statin-induced myopathy.
Question 10: A 72-year-old nursing home resident is complaining of pruritis. She is noted to have multiple, tense blisters on her trunk as well as the flexor surfaces of her extremities. The blisters have an erythematous base. You are unable to extend the blisters when you apply lateral traction. You suspect an autoimmune bullous dermatosis. Which of the following is the cause of the likely condition?
A. Antibodies to epidermal transglutaminase
B. Epidermal necrolysis
C. Antibodies to hemidesmosomes (Correct Answer)
D. Antibodies to desmoglein
E. Antibodies to desmosomes
Explanation: **Antibodies to hemidesmosomes**
- The patient's presentation with **tense blisters** that do not extend with lateral traction (negative Nikolsky sign) is classic for **bullous pemphigoid**.
- **Bullous pemphigoid** is an autoimmune disease caused by antibodies targeting components of the **hemidesmosomes** (specifically BP180 and BP230) at the dermal-epidermal junction.
*Antibodies to epidermal transglutaminase*
- Antibodies against **epidermal transglutaminase** are characteristic of **dermatitis herpetiformis**, which presents with intensely pruritic, grouped vesicles and papules, often on extensor surfaces.
- This condition is also associated with **celiac disease**, and its classic lesions are small and vesicular, not the large, tense bullae described.
*Epidermal necrolysis*
- **Epidermal necrolysis**, including Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN), is characterized by widespread epidermal detachment and necrosis, often triggered by medications.
- It presents with diffuse painful erythema and sheet-like skin loss, which is distinctly different from the described tense blisters of bullous pemphigoid.
*Antibodies to desmoglein*
- Antibodies to **desmoglein 1 and/or 3** (components of desmosomes) are the hallmark of **pemphigus vulgaris** and **pemphigus foliaceus**.
- These conditions cause **flaccid blisters** that are easily ruptured and often exhibit a positive Nikolsky sign, contrary to the tense blisters in this case.
*Antibodies to desmosomes*
- Antibodies to **desmosomes** (specifically desmogleins) lead to **pemphigus**, which is characterized by intraepidermal blistering and a positive Nikolsky sign.
- The described **tense blisters** and negative Nikolsky sign rule out pemphigus, where the defect is in keratinocyte adhesion within the epidermis.
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