Lipoma: Clinical sciences

Lipomas are benign fatty neoplasms that can occur anywhere in the body. While most are solitary, superficial, and limited to the subcutaneous space, some can arise within the deeper soft tissue like the muscle. Sometimes, systemic conditions like lipomatosis can lead to multiple, diffuse or recurrent lipomas. Usually, small and painless lipomas do not require any medical treatment. However, when the mass causes functional or cosmetic dysfunction or is suspicious for malignancy, treatment for removal should be considered.

Alright, when assessing a patient with a chief concern suggestive of lipoma, your first step is to obtain a focused history and physical examination.

Most subcutaneous lipomas are asymptomatic, and are noticed incidentally by the patient on inspection or palpation. History will usually reveal a painless, slow-growing, small, soft, and solitary mass found on the trunk or proximal extremities.

Now, upon a physical exam, you can expect to find a superficial subcutaneous mass that is soft, round, mobile, and well-localized. The mass typically feels doughy with smooth, slippery edges. If these findings are present, you can make your diagnosis of a subcutaneous lipoma.

Superficial lipomas can be diagnosed clinically, so additional work up is not necessary. Your treatment for superficial lipomas depends on the size. For example, small lipomas often can be managed with observation without any intervention; however, if the mass is large, like greater than 5 cm, or if it causes cosmetic concerns, it can be surgically excised.

Here's a clinical pearl! Lipomas can occur anywhere in adipose tissue, including the subcutaneous, intramuscular, gastrointestinal tract, and retroperitoneum. For subcutaneous masses, slippage sign is characteristic for lipoma. It can be elicited by gently sliding fingers off the tumor feeling for its slippery edge, or capsule. Keep in mind that lipomas located deeper within the soft tissue might not elicit this sign very clearly, or at all. Additionally, a lipoma in the GI tract is a very rare type that can arise in the submucosa of the esophagus, stomach, and small intestine. While GI lipomas are benign, it can cause luminal obstruction requiring surgical resection.

Alright, now let’s talk about another type of lipomas that can be found in deeper tissues. On history, you can expect the patient to report a painless, slow-growing, small, solitary mass often on the proximal extremity, like the upper arm or thigh. Patients might also report muscle weakness, pain on active movement, or even decreased range of motion of the affected extremity.

Your physical exam might reveal a deep, round, partially mobile mass that is poorly localized mostly due to the depth of the mass within the soft tissue. Depending on the location of the mass relative to its nearby structure, you might find a reduced distal pulse, tenderness of the mass on palpation, or even paresthesia from compression of the adjacent nerves. If any of these characteristics are present, you should suspect a deep intramuscular lipoma.