20 - 122: LIPOGENIC NEOPLASM Flashcards
It is characterized by a diffused overgrowth of mature adipose tissue infiltrating through preexisting structures.
Lipomatosis
- Diffuse lipomatosis occurs predominantly in children and rarely in adults.
- It is characterized by a diffuse overgrowth of mature lipogenic tissue involving subcutaneous tissue and skeletal muscle of the trunk and the extremities; in addition, osseous involvement may be seen.
- It is a growing mass with predilection of the hand and it is a rare lesion seen in infants and children.
- Clinically, the patients present with a slowly growing mass that is often associated with pain, paresthesia, and sensor or motor deficits
Lipomatosis of the nerve
MC nerve involved in Lipomatosis of the nerve
Median nerve
Followed by the ulnar nerve
It represents a high-grade sarcoma containing a variable number of pleomorphic fibroblasts and it usually shows a predilection for the extremities of adults.
Pleomorphic liposarcoma
Benign neoplasm of brown fat
Hibernoma
- It is a very rare benign mesenchymal neoplasm of deep soft tissue composed of an irregular mixture of mature adipocytes and smooth muscle cells.
- occurs predominantly in females
Myolipoma
It presents as papules, plaques, or solitary lesions with a predilection for the buttocks, upper posterior thighs and lumbar back. In histopathology, it is defined as ill-defined lesions composed of mature adipose tissue that replaces the dermis.
Nevus lipomatosis superficialis
- It presents as painful and tender subcutaneous lesions that occur predominantly at the forearm followed by the trunk, upper arm, and legs.
- occur predominantly in young males
Angiolipoma
- It often presents as asymptomatic, often long standing, mobile tumor in the subcutaneous tissue.
- Histologically, the characteristic feature of this tumor is the additional presence of **multinucleated giant cells **with radially arranged nuclei - floret-like giant cells.
Pleomorphic lipoma
- Painless, slow growing lesions predominantly in infants or children characterized as infiltrative growth that often extends into deeper structures.
- well-circumscribed, lobulated lesions composed of lipogenic cells showing a spectrum of maturation from primitive mesenchymal cells and lipoblasts to mature adipocytes.
- tend to occur on the trunk, at the extremities, and in the head and neck region, whereas visceral involvement and involvement of the retroperitoneum, pelvis, mediastinum, and the abdominal cavity is rarely seen
- st cases present as painless, slowly growing lesions.
Lipoblastoma
Lipoblastoma is a rather well-circumscribed neoplasm whereas lipoblastomatosis is characterized by an infiltrative growth that often extends into deeper structure
most common benign mesenchymal neoplasm
Lipoma
Lipomas may be seen as a manifestation of what syndromes?
- Gardner syndrome - Familial adenomatous polyposis, desmofibromatosis, lipomas, osteomas, cysts
- Bannayan (Bannayan-Riley-Ruvalcaba Syndrome) syndrome: Macrocephaly, lipomas, lymphangiomas, hamartomas, intestinal polyposis, lentigines
Hamartomas, trichilemmomas, lipomas, oral papillomas, palmoplantar keratoses
Cowden syndrome
This gene plays an important role in the pathogenesis of lipoma
HMGA2 gene
Lipomatosis of nerve is a growing mass with a predilection for what area?
Hand
Lipomatosis of nerve is a rare lesion seen in what age group
Infants and children
Lipomatosis of nerve. A, Epineural infiltration of lipogenic cells and collagenous fibrous tissue separating nerve bundles. B, Note the perineural fibrosis.
composed of an irregular mixture of mature adipocytes and smooth muscle cells.
MYOLIPOMA
The most common anatomic site for hibernoma
thigh followed by the trunk, the chest wall, the shoulder area, the upper extremity, and the head and neck area
tumor cells of hibernoma stain positively for S-100 protein and for ___________, a protein unique to brown adipocyte mitochondria
uncoupling protein
Lipomas may be seen as a manifestation of what syndrome?
Gardner syndrome
multiple lipomas together with macrocephaly, lymphangiomas, and hemangiomas are noted in what syndrome?
Bannayan syndrome
Give examples of Syndromes Where Lipogenic Tumors Are Found
Identify the syndrome associated with lipoma with the following features
Familial adenomatous polyposis, desmofibromatosis, lipomas, osteomas, cysts
Identify the syndrome associated with lipoma with the following features
Macrocephaly, lipomas, lymphangiomas, hamartomas, intestinal polyposis, lentigines
Bannayan-Riley-Ruvalcaba syndrome
Identify the syndrome associated with lipoma with the following features
Hamartomas, trichilemmomas, lipomas, oral papillomas, palmoplantar keratoses
Cowden syndrome
Identify the syndrome associated with lipoma with the following features
Intracranial lipomas, hydrocephalus, oculoauriculovertebral dysplasia
Goldenhar-Gorlin syndrome
Identify the syndrome associated with lipoma with the following features
Symmetric lipomas
Myoclonus epilepsy and ragged-red fibers syndrome
Identify the syndrome associated with lipoma with the following features
congenital lipomatosus overgrowth, vascular malformations, epidermal nevi
CLOVE syndrome
Identify the syndrome associated with lipoma with the following features
Cervical lipomas, cerebellar ataxia, photomyoclonus, skeletal deformities
Ekbom syndrome
this gene plays an important role in the pathogenesis of some lipomas
HMGA2 gene
HIV-positive patients treated with what drugs may develop lipodystrophy with increased fat tissue at the neck, the breast, and visceral organs?
protease inhibitors
(atazanavir, darunavir, lopinavir, and ritonavir)
Spindle-cell lipoma Tumor cells stain positively for what stain?
CD34
- presents as a painless, deep-seated mass, and may show a history of recent growth.
- The** proximal extremities and limb girdles** are the most frequently affected anatomic sites, but the trunk and the head and neck region, including the oral cavity, also may be affected
- composed of adipocytes, lipoblasts, and small vacuolated cells.
- A recurrent **t(11;16)(q13;p13) **is seen
Chondroid lipoma
In myolipoma, smooth muscle cells will be positively for what stains?
alpha-smooth muscle actin, desmin, and h-caldesmon
they are composed of large, polygonal, brown fat cells with multivacuolation, granular cytoplasm, and a small, centrally located nucleus admixed with mature white fat cells
Hibernoma
most frequent sarcomas in adults
liposarcomas
- represents the most common pleomorphic sarcoma in the retroperitoneum, and typically affects adult patients in the sixth decade.
- an abrupt or gradual transition from areas showing features of atypical lipomatous tumor to nonlipogenic sarcoma areas is characteristic for this tumor
Dedifferentiated liposarcoma
- represents the second most frequent variant of liposarcoma
- usually occurs in deep soft tissues of the extremities, particularly the thigh, of middle-aged adults
- composed of small, primitive, mesenchymal cells and lipoblasts in** varying stages of differentiation** with a characteristic branching, thin-walled blood vessels
- presence of a round cell component is of adverse significant prognostic importance
- characterized by FUS-DDIT3 or EWSR1-DDIT3 rearrangements
Myxoid liposarcoma
