A case of congenital tectal lipoma found incidentally at an autopsy is reported. This female fetus was a product of pregnancy termination at 24 weeks of gestational age after sonographic detection of hydrocephalus. Autopsy revealed a small mass in the periaqueductal portion. The mass was composed of adipose tissue, cartilage, and mature bony tissue with hematopoiesis. The resultant diagnosis was tectal lipoma with osteocartilagenous element. It is uncertain whether the lesion represents a teratoma or hamartoma or mesenchymal metaplasia. The osteocartilagenous component suggests the latter.
Adult ; Autopsy ; Bone and Bones/pathology ; Brain Neoplasms/*congenital/pathology ; Cartilage/pathology ; Case Report ; *Corpora Quadrigemina/pathology ; Female ; Human ; Infant, Newborn ; Lipoma/*congenital/pathology ; Pregnancy

OBJECTIVETo study the clinicopathologic features of lipomatosis of nerve (NLS).

METHODSThe clinical, radiologic and pathologic features were analyzed in 15 cases of NLS.

RESULTSThere were a total of 10 males and 5 females. The age of patients ranged from 4 to 42 years (mean age = 22.4 years). Eleven cases were located in the upper limbs and 4 cases in the lower limbs. The median nerve was the most common involved nerve. The patients typically presented before 30 years of age (often at birth or in early childhood) with a soft and slowly enlarging mass in the limb, with or without accompanying motor and sensory deficits. Some cases also had macrodactyly and carpal tunnel syndrome. MRI showed the presence of fatty tissue between nerve fascicles, resembling coaxial cable in axial plane and assuming a spaghetti-like appearance in coronal plane. On gross examination, the affected nerve was markedly increased in length and diameter. It consisted of a diffusely enlarged greyish-yellow lobulated fusiform beaded mass within the epineural sheath. Histologically, the epineurium was infiltrated by fibrofatty tissue which separated, surrounded and compressed the usually normal-appearing nerve fascicles, resulting in perineural septation of nerve fascicles and microfascicle formation. The infiltration sometimes resulted in concentric arrangement of perineural cells and pseudo-onion bulb-like hypertrophic changes. The perineurial cells might proliferate, with thickening of collagen fibers, degeneration and atrophic changes of nerve bundles. Immunohistochemical study showed that the nerve fibers expressed S-100 protein, neurofilament and CD56 (weak). The endothelial cells and dendritic fibers were highlighted by CD34. The intravascular smooth muscle cells were positive for muscle-specific actin.

CONCLUSIONSNLS is a rare benign soft tissue tumor of peripheral nerve. The MRI findings are characteristic. A definitive diagnosis can be made with histologic examination of tissue biopsy.

Adolescent ; Adult ; Antigens, CD34 ; metabolism ; CD56 Antigen ; metabolism ; Carpal Tunnel Syndrome ; complications ; pathology ; Child ; Child, Preschool ; Diagnosis, Differential ; Extremities ; innervation ; Female ; Hand Deformities, Congenital ; complications ; pathology ; Humans ; Lipoma ; pathology ; Lipomatosis ; complications ; diagnosis ; metabolism ; pathology ; surgery ; Magnetic Resonance Imaging ; Male ; Median Nerve ; metabolism ; pathology ; Nerve Sheath Neoplasms ; pathology ; Neurofibroma ; pathology ; Neurofilament Proteins ; metabolism ; Neuroma ; pathology ; Peripheral Nervous System Diseases ; complications ; diagnosis ; metabolism ; pathology ; surgery ; Peripheral Nervous System Neoplasms ; pathology ; Retrospective Studies ; S100 Proteins ; metabolism ; Vimentin ; metabolism ; Young Adult