One of the five painful tumors of the skin (see Lists at left)
Very difficult to treat if too many nodules to resect
Recurrences very rare
Bibliography
Hunt SJ, Santa Cruz DJ, Barr RJ. Cellular angiolipoma. Am J Surg Pathol. 1990 Jan;14(1):75-81.
Sciot R, Akerman M, Dal Cin P, De Wever I, Fletcher CD, Mandahl N, Mertens F, Mitelman F, Rosai J, Rydholm A, Tallini G, Van den Berghe H, Vanni R, Willen H. Cytogenetic analysis of subcutaneous angiolipoma: further evidence supporting its difference from ordinary pure lipomas: a report of the CHAMP Study Group. Am J Surg Pathol. 1997 Apr;21(4):441-4.
Lin JJ, Lin F. Two entities in angiolipoma. A study of 459 cases of lipoma with review of literature on infiltrating angiolipoma. Cancer. 1974 Sep;34(3):720-7.
Howard WR, Helwig EB. Angiolipoma. Arch Dermatol. 1960 Dec;82:924-31.
Hattori H. Epidural angiolipoma is histologically distinct from its cutaneous counterpart in the calibre and density of its vascular component; a case report with review of the literature. J Clin Pathol. 2005 Aug;58(8):882-3.
Cina SJ, Radentz SS, Smialek JE. A case of familial angiolipomatosis with Lisch nodules. Arch Pathol Lab Med. 1999 Oct;123(10):946-8.
Variant: Cartilaginous Metaplasia in Lipoma (Chondrolipoma)
Diagnostic Criteria
Lipoma containing areas with true cartilage formation
Ballaux F, Debiec-Rychter M, De Wever I, Sciot R. Chondroid lipoma is characterized by t(11;16)(q13;p12-13). Virchows Arch. 2004 Feb;444(2):208-10.
Gisselsson D, Domanski HA, Hoglund M, Carlen B, Mertens F, Willen H, Mandahl N. Unique cytological features and chromosome aberrations in chondroid lipoma: a case report based on fine-needle aspiration cytology, histopathology, electron microscopy, chromosome banding, and molecular cytogenetics. Am J Surg Pathol. 1999 Oct;23(10):1300-4. Erratum in: Am J Surg Pathol 2000 Jan;24(1):165.
Thomson TA, Horsman D, Bainbridge TC. Cytogenetic and cytologic features of chondroid lipoma of soft tissue. Mod Pathol. 1999 Jan;12(1):88-91.
Kindblom LG, Meis-Kindblom JM. Chondroid lipoma: an ultrastructural and immunohistochemical analysis with further observations regarding its differentiation. Hum Pathol. 1995 Jul;26(7):706-15.
Meis JM, Enzinger FM. Chondroid lipoma. A unique tumor simulating liposarcoma and myxoid chondrosarcoma. Am J Surg Pathol. 1993 Nov;17(11):1103-12.
Bishop E, Eble JN, Cheng L, Wang M, Chase DR, Orazi A, O'Malley DP. Adrenal myelolipomas show nonrandom X-chromosome inactivation in hematopoietic elements and fat: support for a clonal origin of myelolipomas. Am J Surg Pathol. 2006 Jul;30(7):838-43.
Lam KY, Lo CY. Adrenal lipomatous tumours: a 30 year clinicopathological experience at a single institution. J Clin Pathol. 2001 Sep;54(9):707-12.
Variant: Myolipoma of Soft Tissue
Lipoleiomyoma of the uterus and cervix is currently classified as a distinct entity
Diagnostic Criteria
Composed of mature fat and bland smooth muscle
Muscle predominates in most cases
Usually evenly interspersed
Focal smooth muscle overgrowth in one reported case
Muscle in short fascicles
Both components lack any atypical features
No cytologic atypia or lipoblasts
No floret cells
No necrosis
Stroma may be sclerotic or hyalinized
Occasionally myxoid
No prominent vascular component
Occasional features (none affect behavior)
Mitotic figures up to 1/10 HPF
No atypical mitoses
Focal hypercelllularity of spindle cells
Degenerative atypia
Round cell morphology
Hemosiderin
Metaplastic cartilage and bone
Prominent eosinophils
Supplemental Studies
Spindle cells positive for smooth muscle actin, desmin, ER
Other sites include eyelid, spinal cord and pericardium
No known association with tuberous sclerosis
No recurrences or metastsis reported
Bibliography
Takahashi Y, Imamura T, Irie H, Tanaka F, Fukushima J, Fukusato T, Harasawa A, Shiga J. Myolipoma of the retroperitoneum. Pathol Int. 2004 Jun;54(6):460-3.
Guillou L, Coindre JM. Newly described adipocytic lesions. Semin Diagn Pathol. 2001 Nov;18(4):238-49.
Michal M. Retroperitoneal myolipoma. A tumour mimicking retroperitoneal angiomyolipoma and liposarcoma with myosarcomatous differentiation. Histopathology. 1994 Jul;25(1):86-8.
Meis JM, Enzinger FM. Myolipoma of soft tissue. Am J Surg Pathol. 1991 Feb;15(2):121-
Fukushima, Mana MD; Schaefer, Inga-Marie MD; Fletcher, Christopher D.M. MD, FRCPath.Myolipoma of Soft Tissue: Clinicopathologic Analysis of 34 Cases.
American Journal of Surgical Pathology. 41(2):153-160, February 2017..
Largely restricted to back, shoulders, posterior neck
Clinical
No clinical significance to this pattern
Bibliography
Lee HW, Lee DK, Lee MW, Choi JH, Moon KC, Koh JK. Two cases of angiomyxolipoma (vascular myxolipoma) of subcutaneous tissue. J Cutan Pathol. 2005 May;32(5):379-82.
Tardio JC, Martin-Fragueiro LM. Angiomyxolipoma (vascular myxolipoma) of subcutaneous tissue. Am J Dermatopathol. 2004 Jun;26(3):222-4.
Laskin WB, Fetsch JF, Michal M, Miettinen M. Sclerotic (fibroma-like) lipoma: a distinctive lipoma variant with a predilection for the distal extremities. Am J Dermatopathol. 2006 Aug;28(4):308-16.
Rare lipomas have been documented in the retroperitoneum (Macarenco)
Requires extensive sampling to exclude cytologic atypia and lipoblasts
Immunohistochemical and/or genetic studies are recommended before making this diagnosis
Myelolipoma frequently occurs in or around the adrenal
Megakaryocytes should not be confused with atypical cells of ALT
We consider atypical lipomatous tumor and well differentiated liposarcoma to be equivalent terms and primarily use the former, although both are acceptable (see discussion of these terms)
Some use WDL for deep central tumors and ALT for those in other sites
Rare lipomas have been documented in the retroperitoneum (Macarenco)
Requires extensive sampling to exclude cytologic atypia and lipoblasts
Immunohistochemical and/or genetic studies are recommended before making this diagnosis
Myelolipoma frequently occurs in or around the adrenal
Megakaryocytes should not be confused with atypical cells of ALT
We consider atypical lipomatous tumor and well differentiated liposarcoma to be equivalent terms and primarily use the former, although both are acceptable (see discussion of these terms)
Some use WDL for deep central tumors and ALT for those in other sites
Bassett MD, Schuetze SM, Disteche C, Norwood TH, Swisshelm K, Chen X, Bruckner J, Conrad EU 3rd, Rubin BP. Deep-seated, well differentiated lipomatous tumors of the chest wall and extremities: the role of cytogenetics in classification and prognostication. Cancer. 2005 Jan 15;103(2):409-16.
Fletcher CD, Martin-Bates E. Intramuscular and intermuscular lipoma: neglected diagnoses. Histopathology. 1988 Mar;12(3):275-87.
One cytogenetic study has shown findings consistent with ordinary lipoma
Clinical
Benign
Bibliography
Rau T, Soeder S, Olk A, Aigner T. Parosteal lipoma of the thigh with cartilaginous and osseous differentiation: an osteochondrolipoma. Ann Diagn Pathol. 2006 Oct;10(5):279-82.
Petit MM, Swarts S, Bridge JA, Van de Ven WJ. Expression of reciprocal fusion transcripts of the HMGIC and LPP genes in parosteal lipoma. Cancer Genet Cytogenet. 1998 Oct 1;106(1):18-23.
Miller MD, Ragsdale BD, Sweet DE. Parosteal lipomas: a new perspective. Pathology. 1992 Jul;24(3):132-9.
Variant: Lipoma Arborescens / Villous Lipomatous Proliferation of the Synovial Membrane / Synovial Lipomatosis
Diagnostic Criteria
Synovial lined villous proliferation
Villi are diffusely infiltrated by mature fat
Grossly appears as a yellow papillary process
Usually involves large joints
Clinical
May be associated with trauma and arthritis
Fully developed cases are infrequent but fatty infiltration of chronic papillary synovitis is common
May be a reactive process
May present as a chronically swollen joint
Bibliography
Hallel T, Lew S, Bansal M. Villous lipomatous proliferation of the synovial membrane (lipoma arborescens). J Bone Joint Surg Am. 1988 Feb;70(2):264-70.
Variant: Multiple Lipomas
Sporadic
May reach hundreds
Most appear during 40's and 50's
Familial Multiple Lipomatosis
About 1/3 of cases with large numbers of lipomas are familial
The distinction between multiple discrete lipomas and diffuse fatty overgrowth is not always clear
Bibliography
Campen RB, Sang CN, Duncan LM. Case records of the Massachusetts General Hospital. Case 25-2006. A 41-year-old woman with painful subcutaneous nodules. N Engl J Med. 2006 Aug 17;355(7):714-22.
Perriard J, Saurat JH, Harms M. An overlap of Cowden's disease and Bannayan-Riley-Ruvalcaba syndrome in the same family. J Am Acad Dermatol. 2000 Feb;42(2 Pt 2):348-50.
Zigman AF, Lavine JE, Jones MC, Boland CR, Carethers JM. Localization of the Bannayan-Riley-Ruvalcaba syndrome gene to chromosome 10q23. Gastroenterology. 1997 Nov;113(5):1433-7.
Fistarol SK, Anliker MD, Itin PH. Cowden disease or multiple hamartoma syndrome--cutaneous clue to internal malignancy. Eur J Dermatol. 2002 Sep-Oct;12(5):411-21.
Larsson NG, Tulinius MH, Holme E, Oldfors A. Pathogenetic aspects of the A8344G mutation of mitochondrial DNA associated with MERRF syndrome and multiple symmetric lipomas. Muscle Nerve. 1995;3:S102-6.
Traff J, Holme E, Ekbom K, Nilsson BY. Ekbom's syndrome of photomyoclonus, cerebellar ataxia and cervical lipoma is associated with the tRNA(Lys) A8344G mutation in mitochondrial DNA. Acta Neurol Scand. 1995 Nov;92(5):394-7.
Costa T, Fitch N, Azouz EM. Proteus syndrome: report of two cases with pelvic lipomatosis. Pediatrics. 1985 Dec;76(6):984-9.
Clark RD, Donnai D, Rogers J, Cooper J, Baraitser M. Proteus syndrome: an expanded phenotype. Am J Med Genet. 1987 May;27(1):99-117.
Supplemental studies
Immunohistology
Mature fat cells are S100 positive
See specific variant entries for other staining patterns
Rare lipomas have been documented in the retroperitoneum (Macarenco)
Requires extensive sampling to exclude cytologic atypia and lipoblasts
Immunohistochemical and/or genetic studies are recommended before making this diagnosis
Myelolipoma frequently occurs in or around the adrenal
Megakaryocytes should not be confused with atypical cells of ALT
We consider atypical lipomatous tumor and well differentiated liposarcoma to be equivalent terms and primarily use the former, although both are acceptable (see discussion of these terms)
Some use WDL for deep central tumors and ALT for those in other sites
