In most patients, the number and size of cherry angiomas increases with advancing age. They are harmless, having no relation to cancer at all.

Spider angiomas form due to failure of the sphincteric muscle surrounding a cutaneous arteriole. The central red dot is the dilated arteriole and the red "spider legs" are small veins carrying away the freely flowing blood. If momentary pressure is applied, it is possible to see the emptied veins refilling from the centre. No other angiomas show this phenomenon.

The dilation, in turn, is caused by increased estrogen levels in the blood. Many pregnant women, or women using hormonal contraception, have spider angiomas, due to high estrogen levels in their blood. Individuals with significant hepatic disease also show many spider angiomas, as their liver cannot metabolize circulating estrogens, specifically estrone, which derives from the androgen androstenedione. About 33% of patients with cirrhosis have spider angiomas. As such, microhemorrhages may be observed as spider angiomas.

A few studies have worked on providing details related to the outlook of disease progression. Two studies show that each year 0.5% of people who have never had bleeding from their brain cavernoma, but had symptoms of seizures, were affected by bleeding. In contrast, patients who have had bleeding from their brain cavernoma in the past had a higher risk of being affected by subsequent bleeding. The statistics for this are very broad, ranging from 4%-23% a year. Additional studies suggest that women and patients under the age of 40 are at higher risk of bleeding, but similar conducted studies did not reach the same conclusion. However, when cavernous hemangiomas are completely excised, there is very little risk of growth or rebleeding. In terms of life expectancy, not enough data has been collected on patients with this malformation in order to provide a representative statistical analysis.

Spider angiomas are asymptomatic and usually resolve spontaneously. This is common in the case of children, although they may take several years to disappear. If the spider angiomas are associated with pregnancy, they may resolve after childbirth. In women taking oral contraceptives, they may resolve after stopping these contraceptives. The spider angiomas associated with liver disease may resolve when liver function increases or when a liver transplant is performed.

For spider angiomas on the face, techniques such as electrodesiccation and laser treatment can be used to remove the lesion. There is a small risk of a scar, although the results are generally good. Spider angiomas can recur after treatment.

Cherry angiomas occur in all races, ethnic backgrounds, and sexes.

In the treatment of a brain cavernous hemangioma, neurosurgery is usually the treatment chosen. Research needs to be conducted on the efficacy of treatment with stereotactic radiation therapy, especially on the long-term. However, radiotherapy is still being studied as a form of treatment if neurosurgery is too dangerous due the location of the cavernoma. Genetic researchers are still working on determining the cause of the illness and the mechanism behind blood vessel formation. Clinical trials are being conducted to better assess when it is appropriate to treat a patient with this malformation and with what treatment method. Additionally, long term studies are being conducted because there is no information related to the long-term outlook of patients with cavernoma. A registry exists known as The International Cavernous Angioma Patient Registry collects information from patients diagnosed with cavernoma in order to facilitate discovery of non-invasive treatments.

Asplenia is the absence of normal spleen function. It predisposes to some septicemia infections. Therefore, vaccination and antibiotic measures are essential in such cases. There are multiple causes:

- Some people congenitally completely lack a spleen, although this is rare.

- Sickle-cell disease can cause a functional asplenia (or autosplenectomy) by causing infarctions of the spleen during repeated sickle-cell crises.

- It may be removed surgically (known as a splenectomy), but this is rarely performed, as it carries a high risk of infection and other adverse effects. Indications include following abdominal injuries with rupture and hemorrhage of the spleen, or in the treatment of certain blood diseases (Idiopathic thrombocytopenic purpura, hereditary spherocytosis, etc.), certain forms of lymphoma or for the removal of splenic tumors or cysts.

Anti-platelet autoantibodies in a pregnant woman with ITP will attack the patient's own platelets and will also cross the placenta and react against fetal platelets. Therefore, ITP is a significant cause of fetal and neonatal immune thrombocytopenia. Approximately 10% of newborns affected by ITP will have platelet counts <50,000/uL and 1% to 2% will have a risk of intracerebral hemorrhage comparable to infants with neonatal alloimmune thrombocytopenia (NAIT).

No lab test can reliably predict if neonatal thrombocytopenia will occur. The risk of neonatal thrombocytopenia is increased with:

- Mothers with a history of splenectomy for ITP

- Mothers who had a previous infant affected with ITP

- Gestational (maternal) platelet count less than 100,000/uL

It is recommended that pregnant women with thrombocytopenia or a previous diagnosis of ITP should be tested for serum antiplatelet antibodies. A woman with symptomatic thrombocytopenia and an identifiable antiplatelet antibody should be started on therapy for their ITP which may include steroids or IVIG. Fetal blood analysis to determine the platelet count is not generally performed as ITP-induced thrombocytopenia in the fetus is generally less severe than NAIT. Platelet transfusions may be performed in newborns, depending on the degree of thrombocytopenia. It is recommended that neonates be followed with serial platelet counts for the first few days after birth.,

Littoral cell angioma, abbreviated LCA, and formally known as littoral cell angioma of the spleen, is a benign tumour of the spleen that arises from the cells that line the red pulp.

A tufted angioma (also known as an "Acquired tufted angioma," "Angioblastoma," "Angioblastoma of Nakagawa," "Hypertrophic hemangioma," "Progressive capillary hemangioma," and "Tufted hemangioma") usually develops in infancy or early childhood on the neck and upper trunk, and is an ill-defined, dull red macule with a mottled appearance, varying from 2 to 5 cm in diameter.

LCAs most often are not clinically detectable. On occasion, their first presentation may be with splenic rupture.

Most patients show no symptoms and the tumours are found incidentally.

The most common causes of splenomegaly in developed countries are infectious mononucleosis, splenic infiltration with cancer cells from a hematological malignancy and portal hypertension (most commonly secondary to liver disease, and sarcoidosis). Splenomegaly may also come from bacterial infections, such as syphilis or an infection of the heart's inner lining (endocarditis).

The possible causes of moderate splenomegaly (spleen <1000 g) are many, and include:

The causes of massive splenomegaly (spleen >1000 g) are fewer, and include:

- visceral leishmaniasis (kala-azar)

- chronic myelogenous leukemia

- myelofibrosis

- malaria

- splenic marginal zone lymphoma

Splenomegaly is an enlargement of the spleen. The spleen usually lies in the left upper quadrant (LUQ) of the human abdomen. Splenomegaly is one of the four cardinal signs of "hypersplenism" which include; some reduction in the number of circulating blood cells affecting granulocytes, erythrocytes or platelets in any combination, a compensatory proliferative response in the bone marrow, and the potential for correction of these abnormalities by splenectomy. Splenomegaly is usually associated with increased workload (such as in hemolytic anemias), which suggests that it is a response to hyperfunction. It is therefore not surprising that splenomegaly is associated with any disease process that involves abnormal red blood cells being destroyed in the spleen. Other common causes include congestion due to portal hypertension and infiltration by leukemias and lymphomas. Thus, the finding of an enlarged spleen, along with caput medusa, is an important sign of portal hypertension.

The incidence in the general population is roughly 0.5%, and clinical symptoms typically appear between 20 to 30 years of age. Once thought to be strictly congenital, these vascular lesions have been found to occur "de novo". It may appear either sporadically or exhibit autosomal dominant inheritance.

Angioma serpiginosum is characterized by minute, copper-colored to bright red angiomatous puncta that have a tendency to become papular.

Increased platelet counts can be due to a number of disease processes:

- Essential (primary)

- Essential thrombocytosis (a form of myeloproliferative disease)

- Other myeloproliferative disorders such as chronic myelogenous leukemia, polycythemia vera, myelofibrosis

- Reactive (secondary)

- Inflammation

- Surgery (which leads to an inflammatory state)

- Hyposplenism (decreased breakdown due to decreased function of the spleen)

- Splenectomy

- Asplenia (absence of normal spleen function)

- Iron deficiency anemia or hemorrhage

Over-medication with drugs that treat thrombocytopenia, such as eltrombopag or romiplostim, may also result in thrombocytosis.

Other causes include the following

- Kawasaki disease

- Soft tissue sarcoma

- Osteosarcoma

- Dermatitis (rarely)

- Inflammatory bowel disease

- Rheumatoid arthritis

- Nephritis

- Nephrotic syndrome

- Bacterial diseases, including pneumonia, sepsis, meningitis, urinary tract infections, and septic arthritis.

The vast majority of causes of thrombocytosis are acquired disorders, but in a few cases, they may be congenital, such as thrombocytosis due to congenital asplenia.

If splenectomy is performed for conditions in which blood cells are sequestered in the spleen, failure to remove accessory spleens may result in the failure of the condition to resolve. During medical imaging, accessory spleens may be confused for enlarged lymph nodes or neoplastic growth in the tail of the pancreas, gastrointestinal tract, adrenal glands or gonads.

To minimise the risks associated with splenectomy, antibiotic and vaccination protocols have been established, but are often poorly adhered to by physicians and patients due to the complications resulting from antibiotic prophylaxis such as development of an overpopulation of Clostridium difficile in the intestinal tract.

An accessory spleen ("supernumerary spleen", "splenule", or "splenunculus") is a small nodule of splenic tissue found apart from the main body of the spleen. Accessory spleens are found in approximately 10 percent of the population and are typically around 1 centimeter in diameter. They may resemble a lymph node or a small spleen. They form either by the result of developmental anomalies or trauma. They are medically significant in that they may result in interpretation errors in diagnostic imaging or continued symptoms after therapeutic splenectomy.

The basic pathology is some kind of obstructive pathology in the portal, hepatic or splenic vein that causes obstruction of venous blood flow from the spleen towards the heart. The cause of such obstruction may be abnormalities present at birth (congenital) of certain veins, blood clots, or various underlying disorders causing inflammation and obstruction of veins (vascular obstruction) of the liver.

A normal platelet count is considered to be in the range of 150,000–450,000 per microlitre (μl) of blood for most healthy individuals. Hence one may be considered thrombocytopenic below that range, although the threshold for a diagnosis of ITP is not tied to any specific number.

The incidence of ITP is estimated at 50–100 new cases per million per year, with children accounting for half of that amount. At least 70 percent of childhood cases will end up in remission within six months, even without treatment. Moreover, a third of the remaining chronic cases will usually remit during follow-up observation, and another third will end up with only mild thrombocytopenia (defined as a platelet count above 50,000). A number of immune related genes and polymorphisms have been identified as influencing predisposition to ITP, with FCGR3a-V158 allele and KIRDS2/DL2 increasing susceptibility and KIR2DS5 shown to be protective.

ITP is usually chronic in adults and the probability of durable remission is 20–40 percent. The male to female ratio in the adult group varies from 1:1.2 to 1.7 in most age ranges (childhood cases are roughly equal for both genders) and the median age of adults at the diagnosis is 56–60. The ratio between male and female adult cases tends to widen with age. In the United States, the adult chronic population is thought to be approximately 60,000—with women outnumbering men approximately 2 to 1, which has resulted in ITP being designated an orphan disease.

The mortality rate due to chronic ITP varies but tends to be higher relative to the general population for any age range. In a study conducted in Great Britain, it was noted that ITP causes an approximately 60 percent higher rate of mortality compared to gender- and age-matched subjects without ITP. This increased risk of death with ITP is largely concentrated in the middle-aged and elderly. Ninety-six percent of reported ITP-related deaths were individuals 45 years or older. No significant difference was noted in the rate of survival between males and females.

Pneumococcal septicemia, or whole-body infection caused by the "Streptococcus pneumoniae" bacteria, has been reported to cause autosplenectomy but is a very rare and poorly understood complication of the infection.

Splenic diseases include splenomegaly, where the spleen is enlarged for various reasons. On the other hand, a lack of normal spleen function is called asplenia.

Banti's syndrome (also known as Banti's disease), named for is Guido Banti., is a chronic congestive enlargement of the spleen resulting in premature destruction of the red blood cells by the spleen.

Because of the increased risk of infection, physicians administer oral antibiotics as a prophylaxis after a surgical splenectomy (or starting at birth, for congenital asplenia or functional asplenia).

Those with asplenia are also cautioned to start a full-dose course of antibiotics at the first onset of an upper or lower respiratory tract infection (for example, sore throat or cough), or at the onset of any fever.