Presentation
Nape painless swelling appeared about a year ago with stationary size.
Patient Data
Right posterior cervical well-defined intermuscular soft tissue mass lesion. The mass consisted of fat signal interspersed with soft tissue signal. The fatty component is eliciting high signal on T1 and T2 with signal suppression on the fat sat images and no post contrast enhancement ,while the internal soft tissue component eliciting persistent low signal on all pulse sequences with mild post contrast enhancement yet with no diffusion restriction, suggestive of fibrous nature. The lesion displaces the adjacent muscles and causes focal contour bulge.
Provisional diagnosis was posterior neck intermuscular fatty mass containing fibrous tissue (likely fibrolipoma), however atypical lipomatous tumor or well-differentiated liposarcoma could not be ruled out.
The lesion shows mixed fatty and solid components on a non-contrast CT scan of the neck. The solid component contains tiny calcific foci.
Nape sweliing:
Nature of specimen: Excision
Gross: A well-defined swelling. 5.3 x 4 x 5 cm, with bosselated outer surface and focally disrupted capsule (inked all around). Serialling revealed mostly grey white firm branching streaks admixed with soft yellow greasy areas.
Microscopic: Examination of the specimen received revealed pieces of tumor tissue formed of long sweeping fascicles with elongated slender spindle cells with pale cytoplasm within collagenous stroma, showed thin-walled blood vessels with perivascular edema. The tumor was infiltrating the surrounding fat and muscle bundles.
Diagnosis: Benign spindle cell neoplasm suggestive of fibrous hamartoma versus desmoid, for Beta-catenin immunohisochemistry.
Markers: B-catenin and S100
Procedure: Sections were prepared from paraffin blocks treated for B-catenin and S100 automatically stained in Bench mark GX (VENTANA) using VIEW DAB detection kit. Hematoxylin as counter stain.
Results:
Examination of sections treated for B-catenin revealed non nuclear staining of tumor cells by chromogen.
Examination of sections treated for S100 revealed no staining of tumor cells by chromogen.
Diagnosis: Fibrolipoma.
Case Discussion
The signal characteristics of the lesions made it possible to suggest the pathological nature of the lesion despite its rarity. The lesion consisted of a fatty component which elicited high signal on T1 and T2 WI with signal suppression on fat sat sequences and no diffusion restriction nor contrast enhancement, and a fibrous component which elicited typical low signal on all pulse sequences with no diffusion restriction yet with mild patchy contrast enhancement. Hence, provisional diagnosis was fibrolipoma, however, liposarcoma and atypical lipomatous tumor could not be excluded.
The patient had surgical excision of the mass. Histopathology and immunohistochemistry confirmed the diagnosis of fibrolipoma.
Fibrolipoma is a rare neoplasm that is defined as a subtype of lipoma containing significant fibrous tissue. This might occur in the oral cavity, parotid gland, esophagus, intestine, and other areas.
It's important to differentiate between lipoma, lipoma variants and well-differentiated liposarcomas/ atypical lipomatous tumors.
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