A Hamartoma is mostly a benign mass of disorganized tissue native to a particular anatomical location. Most of the hamartomas are usually benign, but malignant transformation may occur. Hamartomas can grow almost anywhere on the body and usually are found in the lungs, hypothalamus, breast, and colon, etc.
Most of the cases are asymptomatic and discovered incidentally during the evaluation of other medical conditions. Hamartomas cause morbidity by various mechanisms such as; infection, infarction, pressure/obstruction, hemorrhage/anemia, fracture, neoplastic transformation.
Hamartomas result from the abnormal formation of normal tissue and sometimes occur sporadically and a few times as a part of a syndrome. Hamartoma is most likely due to a developmental error and may appear in several sites. It grows at the same rate as of the original tissue. There are also some genes involved in the pathogenesis of the development of hamartoma include SMAD4, PTEN, STK1, BMPR1A.
There are many hereditary syndromes associated with hamartomatous formation include:
Generally, males are affected more commonly than females by hamartomas. There is no particular evidence of racial predilection. The incidence of most of the hamartomas remains unknown except pulmonary hamartoma, in which the incidence rate is approximately 0.25%. Pulmonary hamartomas are 8% of all lung tumors; most of them are diagnosed incidentally. The most common patient age range is 40 to 70.
Hamartomas are fundamentally comprised of disordered replications of normal tissue cells. The underlying mechanisms of anomalous replications are not fully recognized. The distinct property is a clearly demarcated mass mainly containing fat and cartilage, but other tissue cells may also be present depending on the anatomic location. The size of most of the hamartomas is between 1 to 3 cm. Hamartomas are usually not encapsulated and have multiple lobes divided by septations. 
On microscopic examination, hamartomas have characteristics similar to any benign tumor, such as haphazard growth of the normal tissue and architectural pattern of cytologically normal cells native to the local site. There is usually no sign of metastasis or local invasion.
Usually, adipocytes and single chondrocytes appear in lacunae with the abundant neighboring matrix, and some other cell types may also be found depending on the site of origin.
History taking is a significant aspect of creating the diagnosis of hamartoma and related syndromes. It is crucial in understanding the cause and associated conditions. Although usually, hamartomas are asymptomatic, complete family and case history can help to determine the prognosis. Patient history specific to the related condition is also necessary. Common symptoms and physical findings related to the site of origin as follows:
Hypothalamus: seizure, altered mental status, vision changes, early-onset pubarche, behavioral changes.
Lung: chronic cough, hemoptysis, fever, respiratory sounds, e.g., coarse crackles on inspiration, obstructive symptoms
Heart: chest pain, palpitations, edema, dyspnea, cyanosis, cool and clammy skin, murmur, arrhythmia
Other less common symptoms and physical findings involving kidney, spleen, and other organs include flank pain, abdominal pain, recurrent infections, fever, night sweats, palpable abdominal mass, increased testicular size, and increased breast size.
On chest radiography, lung hamartomas characteristically demonstrate sharply demarcated pulmonary nodules and popcorn calcification. There are no CXR findings associated with other types of hamartomas.
On CT scan, a hamartoma demonstrates localized collections of fat alternating with foci of calcification. It is the diagnostic imaging test of choice.
On MRI, hamartoma is specified by a heterogeneous signal in T1 and high signal because of fat and cartilaginous components in T2. It is the diagnostic imaging test of choice of the hypothalamus and most of the abdominal visceral hamartomas, i.e., kidney, spleen, pancreas.
Ultrasound can prove beneficial in the diagnosis of splenic hamartomas.
Bronchoscopy is useful in the diagnosis of endobronchial hamartomas.
Most of the cases of hamartoma are asymptomatic and found incidentally. Other patients are treated conservatively with supportive management. Surgical treatment is a consideration in unresponsive patients, and it is the treatment modality of choice for hamartomas. Surgery is also indicated for diagnostic confirmation, mass symptoms, and for cosmetic reasons.
The following are some conditions that have overlapping presentations with hamartoma and require evaluation.
Following are some different treatment modalities for differing anatomical sites
High dose radiations on a focused location such as the hypothalamus hamartomatous lesion can be effective. Gamma knife radiosurgery uses highly focused gamma rays, and therefore it is a distinctly precise procedure.
Although it uses highly focused radiation beams and relatively safer than traditional radiation therapy, it can also cause various adverse effects such as nausea, vomiting, fatigue, skin blistering, dysphagia, brain edema, and headache. Longterm treatment with radiation also increases the risk.
Hamartomas are usually benign, but malignant transformation may occur in some cases, e.g., in Cowden syndrome, where there is an increased risk of breast, thyroid, and endometrial cancer. The prognosis of hamartoma usually depends on the location and size of the mass and the comorbid conditions. Large-sized masses in the kidneys hypothalamus or spleen pose more significant health issues.
Hamartomas can grow to enormous sizes and cause disfigurement and pressure on surrounding organs internally, which can lead to life-threatening symptoms. It can lead to seizures, heart failure, breathing difficulty, breast deformity, and abdominal pain, etc.
There are various non-profit organizations devoted to education, information provision, and support to hamartoma patients, and healthcare providers while promoting research towards early detection, better treatments, quality of life, and cure.
Although hamartomas are usually benign, they should be monitored continuously for malignant potential. The interprofessional team is generally necessary due to the complex and diverse presentation of patients. For a better outcome, a screening program should be in place for the earlier detection. Good communication, along with detailed and smooth information sharing, are essential components for better outcomes. The interprofessional care must involve an evidence-based approach to planning and evaluation of the cases.
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