Hamartomas must be differentiated from other diseases that result on fat containing lesions such as lipomas and metastases.
Differentiating Hamartoma from other Diseases
Hypothalamic hamartomas
The differential diagnosis is broadly that of suprasellar and hypothalamic lesions, although the imaging characteristics of hypothalamic hamartomas significantly reduces the differential.
Hypothalamic-chiasmatic glioma is the main differential.
Most other lesions encountered in the region either have markedly different signal intensity or demonstrate enhancement on MRI.[1]
The table below summarizes the findings that differentiate hypothalamic hamartoma from other conditions that are also suprasellar and hypothalamic lesions. [2]
Rathke's cleft cyst is a benign growth found on the pituitary gland in the brain, specifically a fluid-filled cyst in the posterior portion of the anterior pituitary gland
Rathke's cleft cyst occurs when the Rathke's pouch does not develop properly and ranges in size from 2 to 40mm in diameter
Asymptomatic cysts are commonly detected during autopsies in 2 - 26% of individuals who have died of unrelated causes
Females are twice as likely as males to develop a cyst
Pituitary macroadenoma is a common pituitary gland tumor
Patients with pituitary adenoma may progress to develop lethargy, headache, nausea, and vomiting
Common complications of pituitary adenoma include bitemporal hemianopia, anosmia, acromegaly, and gigantism
Pulmonary hamartomas
The differential is dependent on whether fat or calcification is identifiable within the lesion. If fat is visualized then the differential is narrow, with almost all cases representing pulmonary hamartoma.
The presence of calcification also significantly narrows the differential, but to a lesser degree.
If neither fat, nor calcification is present, then the differential is that of a solitary pulmonary nodule and is significantly broader.
The table below summarizes the findings that differentiate pulmonary hamartoma from other conditions that cause a fat containing solitary pulmonary nodule.
Pulmonary metastases are common and usually asymptomatic, with constitutional symptoms relating to disseminated metastatic disease and those attributable to the primary tumour dominating
Common symptoms include hemoptysis and pneumothorax
Pulmonary metastases tend to be single or multiple[1]
Pulmonary Chondroma
Pulmonary chondromas are usually associated with Carney’s triad
On CT scan, chondromas appear as smoothly marginated, round, or slightly lobulated, small areas of fat
Pulmonary chondromas are common in adolescents or young adults[4]
Heart
The table below summarizes the findings that differentiate cardiac hamartoma from other conditions that cause a fat containing lesion within the striated muscle of the heart.
Disease
Findings
Hibernoma
Hibernoma is a benign neoplasm of vestigial brown fat
The majority of patients present with a slow-growing, painless, solitary mass, usually of the subcutaneous tissues
It is much less frequently noted in the intramuscular tissue. It is not uncommon for symptoms to be present for years
In general, imaging studies show a well-defined, heterogeneous mass, usually showing a mass which is hypointense to subcutaneous fat on magnetic resonance T1-weight images. Serpentine, thin, low signal bands (septations or vessels) are often seen throughout the tumor
Any primary malignancy may metastasize to the heart, however, lung cancer is among the most common.[5]
Spleen, kidneys and vascular organs
The table below summarizes the findings that differentiate spleen, kidneys and vascular organs from other conditions that cause a incidental findings that resemble hamartoma.
Retroperitoneal liposarcoma is the most common primary retroperitoneal neoplasm
Retroperitoneal liposarcoma is a subtype of liposarcoma, a malignant tumour of mesenchymal origin that may arise in any fat-containing region of the body
Adrenolipomas are rare benign neoplasms that histologically consist of fat and bone marrow in varying proportions
In general, most tumors are unilateral, they show no predilection to one peculiar side. Symptoms of adrenolipoma include abdominal pain, haematuria, and abdominal fullness
They are rich in adipose tissue and hematopoietic elements
Most lesions are small and asymptomatic
Adrenolipomas are usually detected incidentally in autopsy or by imaging studies performed for other reasons