We are celebrating the first year of this project with a new article on pathognomonic signs; the previous one was our first and most successful article to date. There was no better topic to celebrate our first year of bringing science closer to everyone.
Below, we present the 13 strangest pathognomonic signs that can be found in medical practice. But first, we'll briefly review their meaning and importance.
What are pathognomonic signs?
Pathognomonic signs are unique symptoms of a disease, meaning they can only occur in one specific illness. Therefore, if you observe one of these symptoms, you can accurately diagnose the ailment the patient is experiencing.
Pathognomonic signs are rare because there aren't many that meet this condition. Most symptoms of a disease can also appear in others, making it necessary for diagnosis to combine several signs along with diagnostic tests, rather than being able to diagnose it directly with a single symptom.
The 13 strangest pathognomonic signs - The last one will shock you
1. Stone man syndrome
Fibrodysplasia ossificans progressiva (FOP) - Münchmeyer disease
Description
A rare disease affecting around 3,000 people worldwide, which causes cells of soft tissues like ligaments and tendons to be replaced by bone cells during cellular regeneration. This leads these tissues to ossify and gradually turn into bones.
In individuals with FOP, even minor trauma can trigger bone formation in areas where it normally shouldn't occur, leading to a progressive loss of mobility and the development of a sort of "secondary skeleton" outside the normal skeletal system.
Cause
The disease is caused by a mutation in the ACVR1 gene, which regulates bone growth. It is an autosomal dominant hereditary disease, meaning that if one parent has the condition, their offspring have a 50% chance of inheriting it. If both parents have it, all their descendants will as well.
Treatment
There is currently no cure, and treatments are very limited due to the complexity of the disease. Therefore, the treatment is merely preventive and palliative.
Source: https://www.linkedin.com/pulse/fibrodysplasia-ossificans-progressiva-drug-market-review-hussain
2. Reed-Sternberg cells
Lymphatic cancer - Hodgkin's lymphoma
Description
Reed-Sternberg cells are abnormal, large cells typically found in Hodgkin's lymphoma, a type of cancer of the lymphatic system. These cells usually have one or two large, prominent nuclei, giving them an "owl's eye" appearance under the microscope. They are considered a distinctive feature for diagnosing this lymphoma, and the presence of Reed-Sternberg cells is essential to differentiate Hodgkin's lymphoma from other types of lymphomas.
Cause
They originate from B lymphocytes that have undergone a genetic mutation due to the disease.
Treatment
Hodgkin's lymphoma is usually treated primarily with chemotherapy but can also be managed with a combination of other techniques such as radiotherapy, immunotherapy, targeted therapy, or bone marrow transplantation.
3. Romaña's sign
Chagas disease
Description
Romaña's sign is a characteristic symptom of the acute phase of Chagas disease. It presents as a painless, unilateral swelling of one of the eyelids, usually accompanied by redness and edema (swelling) around the eye.
Cause
This sign occurs when the parasite Trypanosoma cruzi enters the body through the mucous membranes of the eye, often happening when the infected feces of the triatomine insect are accidentally rubbed into the ocular area.
Treatment
Antiparasitic drugs like benznidazole and nifurtimox.
4. Boot sign or Dutch clog sign
Heart disease - Tetralogy of Fallot
Description
The boot sign (also known as the Dutch clog sign) is a characteristic image observed on chest X-rays of patients with tetralogy of Fallot. This appearance is due to the peculiar shape the heart adopts in this condition, where the right ventricle is enlarged, causing the heart's apex to lift slightly upwards, giving it an appearance similar to a boot or Dutch clog.
This radiological sign is indicative of right ventricular hypertrophy and the altered anatomy of the heart's arteries typical of this congenital heart disease.
Cause
Tetralogy of Fallot is a complex congenital heart disease that arises during fetal development and has multifactorial causes, including genetic factors like DiGeorge syndrome and environmental factors such as maternal exposure during pregnancy to viral infections, uncontrolled diabetes, or alcohol consumption.
This condition is characterized by four main cardiac anomalies:
- Pulmonary stenosis: Narrowing of the pulmonary valve or artery that reduces blood flow to the lungs.
- Ventricular septal defect (VSD): A hole in the wall that separates the left and right ventricles, allowing blood to mix between them.
- Right ventricular hypertrophy: Thickening of the right ventricular muscle due to the extra effort required to pump blood through the narrowed pulmonary artery.
- Overriding aorta: The aorta is displaced over the ventricular septal defect, allowing it to receive blood from both ventricles.
Treatment
The treatment of tetralogy of Fallot is surgical and involves correcting the structural defects. The main approaches include:
- Complete repair surgery: Usually performed in early childhood. This surgery involves closing the ventricular septal defect (VSD) with a patch and enlarging the pulmonary artery and/or its valve to improve blood flow to the lungs.
- Palliative procedure (Blalock-Taussig shunt): Performed in some cases where the baby is too small or fragile for complete repair. A conduit is placed between the subclavian artery and the pulmonary artery to temporarily improve blood flow to the lungs and enhance oxygenation until the child can undergo corrective surgery.
With appropriate treatment, many people with tetralogy of Fallot can lead relatively normal lives, although long-term medical follow-up is required to monitor cardiac function.
5. Pericardial friction rub sign
Acute pericarditis
Description
The pericardial friction rub sign is a characteristic sound heard during cardiac auscultation in patients with acute pericarditis. This sound is similar to a squeaking or scratching noise and is produced by the rubbing of the inflamed pericardial layers, which is the sac surrounding the heart. The pericardial rub is usually best heard at the left sternal border of the chest and changes with the patient's position, often being more audible when the patient leans forward.
Cause
Acute pericarditis, which causes this sign, is the inflammation of the pericardium and can have various causes. Viral infections, such as those caused by coxsackievirus and influenza virus, are the most frequent culprits. However, the inflammation can also appear as a complication of an acute myocardial infarction (AMI), either immediately or weeks later in what is known as Dressler's syndrome. Additionally, autoimmune diseases like systemic lupus erythematosus or rheumatoid arthritis, recent cardiac trauma or surgeries, advanced renal failure, and certain cancers or treatments (such as radiotherapy) can trigger pericarditis.
Treatment
The treatment of acute pericarditis focuses on reducing inflammation and relieving symptoms. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or aspirin are used for this purpose, usually administered for one or two weeks and adjusted according to the patient's response. In more persistent cases, colchicine can be added to the treatment, as it helps reduce the duration of symptoms and prevent recurrences. If the patient does not respond adequately or the pericarditis is a consequence of an autoimmune disease, corticosteroids may be an option, although they are reserved for specific situations due to the increased risk of recurrences.
When pericarditis is caused by bacterial infections, the treatment includes antibiotics and, in some cases, drainage of the pericardial fluid. If the inflammation is due to another condition, such as renal failure, the treatment will focus on controlling the underlying disease. In severe cases of significant accumulation of fluid in the pericardium (pericardial effusion) or if the inflammation affects cardiac function and causes tamponade, it may be necessary to perform a pericardiocentesis to drain the fluid and relieve pressure on the heart.
6. Gottron's sign
Dermatomyositis
Description
Gottron's sign is a characteristic skin manifestation of dermatomyositis, an autoimmune disease that primarily affects the muscles and skin. This sign appears as raised, reddish or violaceous areas with a scaly texture, occurring on the knuckles, elbows, and knees. These lesions are a distinctive marker of dermatomyositis and are often accompanied by other skin symptoms, such as heliotrope rash—a reddish discoloration around the eyes.
Cause
Dermatomyositis is an autoimmune disease in which the immune system mistakenly attacks muscle tissue and skin, causing inflammation and damage. Although the precise cause is unknown, it is believed that genetic factors, viral infections, and certain types of cancer can trigger the disease. In some adults, dermatomyositis presents as a paraneoplastic condition, meaning it appears associated with certain types of cancer.
Treatment
The treatment of dermatomyositis focuses on reducing inflammation and controlling symptoms. Corticosteroids like prednisone are the initial treatment and are usually administered in high doses for a rapid response. In cases where the disease does not respond adequately to corticosteroids or requires long-term control, immunosuppressants such as methotrexate or azathioprine are used to reduce immune activity. For patients with severe skin symptoms, antimalarials like hydroxychloroquine can be helpful in treating skin lesions.
7. Lisch nodules
Neurofibromatosis type 1
Description
Lisch nodules are small pigmented spots or bumps that appear on the iris of the eye and are a common feature of neurofibromatosis type 1 (NF1). These nodules are usually light brown or golden in color and do not affect vision, but their presence is useful for diagnosing NF1, especially since they often appear in childhood and are easily observable during an eye examination.
Cause
Neurofibromatosis type 1 is a genetic disorder that affects the development and growth of nerve cells. It is caused by mutations in the NF1 gene located on chromosome 17, which encodes a protein called neurofibromin. This protein acts as a tumor suppressor, helping regulate cell growth. When the NF1 gene is mutated, this regulatory function is impaired, leading to the development of benign tumors on nerves (neurofibromas) and other clinical manifestations like café-au-lait spots on the skin and Lisch nodules in the eyes. NF1 is hereditary and follows an autosomal dominant inheritance pattern, although it can also arise from spontaneous mutations.
Treatment
The treatment of neurofibromatosis type 1 focuses on managing symptoms and complications since there is no cure for the disease. Patients often need regular evaluations to detect growth problems, developmental issues, and possible neurological, bone, or vascular complications. Neurofibromas can be surgically removed if they cause pain, functional problems, or are in areas that affect the patient's appearance. In some cases, pharmacological treatments or targeted therapies can be used to reduce the size of neurofibromas, especially if they affect critical areas or are very numerous. Physical therapy and educational support are also important to help patients cope with motor problems or learning difficulties that may be associated with NF1.
8. Popeye sign
Rupture of the long head of the biceps brachii tendon
Description
The Popeye sign is a visual deformity that occurs in the arm after the rupture of the biceps tendon, usually of the distal tendon or the long tendon of the proximal portion of the biceps. This sign is characterized by a bulge in the upper part of the arm that resembles the bulging biceps of the cartoon character Popeye. The deformity is caused because, upon tendon rupture, the muscle retracts toward the shoulder and accumulates in a "lump."
Cause
The most common cause of this injury is excessive strain or a sudden movement that exerts too much tension on the tendon, especially when lifting heavy objects. Sports involving weightlifting, intense physical labor, or falls where the arm absorbs the impact can lead to this type of rupture. It can also develop in people with prior tendon degeneration due to age or accumulated micro-tears, making it more vulnerable to a complete rupture.
Treatment
The treatment of the Popeye sign depends on the severity of the injury and the patient's needs. In young, active individuals or athletes, surgical repair is usually recommended to reattach the tendon and restore full biceps function, especially because the distal tendon is important for supination strength (turning the palm upward) and elbow flexion. Conversely, in older people or those who do not require full biceps function, conservative treatment may be sufficient, involving rest, physical therapy, and pain management with analgesics.
Source: https://www.nejm.org/doi/abs/10.1056/NEJMicm1704705
9. Auspitz sign
Psoriasis
Description
The Auspitz sign is a characteristic finding in patients with psoriasis. It is observed when, upon gently scraping a psoriatic lesion, pinpoint bleeding appears on the skin's surface, similar to tiny drops of blood. This sign occurs because psoriatic skin has a thinner epidermal layer over the dermal blood vessels, and when this layer is removed by scraping, these vessels are exposed, causing bleeding. The Auspitz sign is useful for diagnosing psoriasis, although it is not exclusive to this disease.
Cause
Psoriasis is a chronic inflammatory skin disease of autoimmune origin. It occurs when the immune system mistakenly attacks skin cells, causing them to multiply abnormally fast. This leads to the accumulation of cells on the skin's surface, forming scaly and reddened plaques. The exact causes of psoriasis are not fully understood, but it is believed to result from a combination of genetic and environmental factors. Various triggers, such as stress, infections, skin injuries, certain medications, and alcohol or tobacco use, can worsen or precipitate outbreaks in genetically predisposed individuals.
Treatment
The treatment of psoriasis depends on the severity and extent of the disease. In mild cases, topical treatments are usually employed, such as creams with corticosteroids, vitamin D analogs (calcipotriol), retinoids, and coal tar, which help reduce inflammation and plaque thickening. In moderate to severe cases, treatment may include ultraviolet light therapy (phototherapy), which helps reduce cell proliferation in psoriatic plaques.
For severe or resistant cases, systemic treatments are used, such as immunosuppressive medications (methotrexate, cyclosporine) or biological agents. Biological agents are more specific medications designed to block key molecules of the immune system that trigger inflammation in psoriasis, such as TNF-alpha inhibitors or interleukin-17 inhibitors. Additionally, treatment is often complemented with supportive measures like moisturizers to improve the skin barrier and recommendations to avoid triggering factors.
Source: https://genevadermatology.ch/psoriasis-auspitz-sign/
10. Eiffel Tower at night sign
Idiopathic hypertrophic pachymeningitis
Description
The "Eiffel Tower at night" sign is a finding observed in magnetic resonance imaging (MRI) studies of patients with idiopathic hypertrophic pachymeningitis (IHP). This sign is characterized by symmetrical thickening of the dura mater (the outer layer of the meninges) in the falcotentorial region, forming an image that, in coronal view, resembles the silhouette of the Eiffel Tower illuminated at night. It is a sign that helps differentiate IHP from other meningeal diseases, although it is not specific to this pathology. Therefore, while it may not be strictly pathognomonic, it does guide the diagnosis quite accurately.
Cause
Idiopathic hypertrophic pachymeningitis is a rare and chronic inflammatory condition that causes progressive thickening of the dura mater. This inflammation can lead to symptoms such as persistent headaches, focal neurological deficits, and, in some cases, visual and auditory disturbances due to compression of cranial nerves. Although the cause of IHP is unknown, it is classified as idiopathic because it is not associated with infections, cancers, or systemic autoimmune diseases when it presents as an isolated disorder. However, in some patients, an abnormal immune response targeting the dura mater is suspected, triggering inflammation and thickening.
Treatment
The treatment of idiopathic hypertrophic pachymeningitis focuses on reducing inflammation and controlling symptoms. Corticosteroids are the first-line treatment and are usually administered in high doses initially to rapidly reduce meningeal inflammation. In cases where corticosteroids are not sufficiently effective or long-term treatment is required, immunosuppressants like methotrexate or azathioprine are used to control inflammation without the side effects associated with prolonged steroid use.
Source: https://www.semanticscholar.org/paper/%E2%80%98Eiffel-by-Night%E2%80%99%3A-A-New-MR-Sign-Demonstrating-in-Thomas-Thamburaj/ebef293392f35dd81d17bef13e6d3c6a51b3e21e
11. Donald Duck sign
Rhombencephalosynapsis
Description
The Donald Duck sign is a characteristic finding in neuroimaging studies, especially MRI scans, observed in patients with rhombencephalosynapsis. In this condition, the anomalous fusion of the cerebellum causes the brainstem structure to adopt a shape reminiscent of the cartoon character Donald Duck. This peculiar shape is due to the absence of the cerebellar vermis (the central part that normally separates both cerebellar hemispheres) and the fusion of the cerebellar hemispheres, generating a distinctive appearance in the images.
Cause
Rhombencephalosynapsis is an extremely rare congenital disorder characterized by the absence of the cerebellar vermis and the consequent fusion of the cerebellar hemispheres. Although the exact causes are unknown, it is believed to be an anomaly of embryonic development in which a genetic alteration or interruption in early nervous system formation affects the normal development of the cerebellum. Rhombencephalosynapsis can manifest as an isolated condition or as part of complex genetic syndromes and is often accompanied by other cerebral malformations or neurological symptoms such as coordination problems, motor difficulties, visual alterations, and, in some cases, intellectual disability or balance issues.
Treatment
The treatment of rhombencephalosynapsis is symptomatic and depends on the specific symptoms each patient presents, as there is no cure for the structural anomaly. Generally, supportive therapies are used, including physical therapy and occupational therapy to help improve motor skills and coordination. In cases with visual alterations or balance problems, treatment may include specific exercises for vestibular and visual rehabilitation. If there is epilepsy or seizures, anticonvulsants can be employed to control these episodes.
12. Lazarus sign
Brain death
Description
The Lazarus sign is a phenomenon that can occur in patients with brain death or those who are clinically dead but under mechanical ventilation support. It manifests as automatic movements of the arms, which seem to rise and fall over the chest in a posture similar to a "resurrected corpse." These movements can appear deliberate or even as if the patient is attempting to cross their arms over the chest, creating an impactful and sometimes confusing image for onlookers. Despite its appearance, the Lazarus sign does not indicate consciousness or brain activity but is a spinal reflex activated by the release of electrical impulses in the spinal cord when the brain is no longer functioning.
Cause
The causes of the Lazarus sign are related to the residual activity of spinal reflexes in patients with brain death. When the brain ceases to function, the spinal cord can continue generating involuntary reflexes due to the absence of cerebral inhibition. These reflexes can be triggered by external stimuli, such as movement or manipulation of the body, and manifest as spontaneous movements without any involvement of consciousness or brain control.
Treatment
Treatment of the Lazarus sign is not actually necessary, as this phenomenon does not represent a medical problem in itself but a physical reflex in people without brain activity. However, it is important for the medical team and the patients' families to understand this phenomenon to avoid confusion or erroneous interpretations about the patient's state. In some cases, sedatives can be administered or certain reflexes blocked to minimize the occurrence of these movements, especially if they are unsettling for family members or staff. Proper understanding and communication about the Lazarus sign are essential for ethical and emotional management in palliative care contexts or in patients diagnosed with brain death.
13. Lichtenberg figures
Lightning strike
Description
The Lichtenberg figure, also known as the Lichtenberg sign or arborescent marks, is a characteristic skin marking that appears on people who have been struck by lightning. These marks, which are usually temporary, have an appearance similar to tree branches or a fern pattern and are caused by the electrical discharge of the lightning passing through the skin, causing minor damage to capillary blood vessels. Although Lichtenberg figures can be visually impressive, they generally do not cause pain and disappear spontaneously within hours or days.
Cause
The causes of the Lichtenberg figure are due to the injury caused by the passage of lightning's electricity through the body. The high energy of the lightning causes the rupture of small blood vessels in the skin, forming these arborescent marks. Besides these superficial marks, a lightning strike can cause other serious internal damages, such as cardiac arrhythmias, neurological injuries, burns, or damage to internal organs due to the intensity of the current and the shock wave of the lightning.
Treatment
Treatment of the Lichtenberg figure itself is not necessary, as the marks are usually temporary and do not represent deep skin damage. However, a lightning strike can cause serious complications, so treatment should focus on evaluating and addressing any possible associated injuries. First aid includes immediate assessment of airway, breathing, and circulation, as lightning strikes can cause cardiac or respiratory arrest. The patient should be monitored for cardiac arrhythmias and other internal damages.
Source: https://www.europapress.es/desconecta/curiosity/noticia-figuras-lichtenberg-esto-le-pasa-piel-si-te-alcanza-rayo-20160216135751.html
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