Skeletal Radiol (1992) 21:414~417
Skeletal Radiology
Case report 751 I.J. Braunschweig, M.D. 1, I.H. Stein, M.D. 1, M.I.M. Dodwad, M.D. 2, A.F. Rangwala, M.D. 2, and A. Lopano, M.D. 3 Departments of 1 Radiology, 2 Pathology, and 3 Orthopedic Surgery, Monmouth Medical Center, Long Branch, New Jersey, USA
Imaging studies Fig. 1. AP projection of the left foot reveals marked erosion of the 2nd, 3rd, and 4th metatarsals. Lucency is noted throughout the soft tissues, which represents the lipomatous mass Fig. 2. Axial CT image reveals a large, well-circumscribed, but lobulated soft-tissue mass of low attenuation (--107 to --111 H.U,). Marked erosion of the metatarsals adjacent to the mass is noted
Address reprint requests to. l.J. Braunschweig, M.D., Department of Radiology, Monmouth Medical Ccnter, Long Branch, NJ 07740, USA
9 1992 International Skeletal Society
I.J. Braunschweig et al. : Case report 75l
415 Clinical information
Fig. 3. Tl-weighted axial image reveals a lobulated mass of increased signal in the metatarsal region with extensive deformity of the adjacent bones Fig. 4. Axial T2-weighted image reveals a mass of slightly less signal than seen on TI yet greater than adjacent muscle tissue
A 73-year-old w o m a n was admitted to our institution with a fracture of the proximal area of the right humerus following a fall, which necessitated open reduction. Initial physical examination revealed a palpable, soft mass on the dorsum of the left foot. The patient stated that the mass had been present for m a n y years without significant change. Following surgical repair of the fractured humerus, work-up of the lesion of the left foot proceeded. Plain films, CT and M R I of the left foot revealed a lobulated soft-tissue mass with marked erosion of the 2nd, 3rd, and 4th metatarsals (Fig. 1). A C T scan showed the mass to be of fat attenuation, ranging from - 1 0 7 to - 1 1 1 Hounsfield Units (Fig. 2). M R I revealed a lobulated mass of increased signal on T I (Fig. 3). T2-weighted images demonstrated a mass of slightly less signal than that noted on T I yet still greater than adjacent muscle tissue (Fig. 4). Although the mass appeared to be a well-circumscribed, lipomatous lesion, the uncharacteristically extensive degree of bone erosion necessitated an incisional biopsy.
416
Diagnosis: Spindle cell lipoma causing marked bone erosion Histological examination of the tissue specimens revealed benign adipose tissue in a lobulated pattern, admixed with regions of myxoid tissue with a proliferation of spindle cells. Minimal cellular pleomorphism and increased vascularity were identified. The lesion was seen to infiltrate into adjacent bone, with erosion of the cortex (Figs. 5-7).
Discussion Prior to its initial description in the literature, spindle cell lipoma was frequently misdiagnosed as liposarcoma [9, 10]. The present case provided a similar diagnostic dilemma. Spindle cell lipoma typically is encountered in men between the ages of 45 and 65 years. This tumor has most frequently been found in the subcutaneous tissues of the posterior segments of the neck and shoulder, although various other presentations have been described [1, 12, 15, 16, 18]. These tumors are painless, slowly growing and often present for years and have the potential to infiltrate into adjacent tissue. Histological diagnosis of spindle cell lipoma is based upon the homogeneous relationship of spindle cells to the collagen fibrils and the absence of lipoblasts [3, 8]. Liposarcoma is the second most c o m m o n soft-tissue sarcoma encountered in the adult population [2].
Histology studies 1 Fig. 5. Spindle cell lipoma shows a mixture of mature fat cells with uniform spindle cells. The spindle cells are associated with a mucoid matrix. An increase in the amount of collagen is present. (H & E, x 140) Fig. 6. The spindle cell lipomatous mass infiltrates into the adjacent bony tissue (low power magnification). (H & E, x 100) Fig. 7. Low power magnification shows another area with destruction and erosion of bone by spindle cell lipoma. (H & E, x 100) 1 Diagnosis concurred by Sharon W. Weiss, M.D., Director of Anatomical Pathology, University of Michigan Medical Center, Ann Arbor, Michigan
I.J. Braunschweig et al. : Case report 751
I.J. Braunschweig et al. : Case report 751 Most patients with liposarcomas present in the 5th and 6th decades (similar to spindle cell lipoma). Liposarcomas are usually found in the extremities (most c o m m o n l y the thigh) and the retroperitoneum. Liposarcom a is very rarely seen in the distal aspect of the extremities. The majority of patients present with a painless mass; however, a small percentage of patients experience pain and tenderness. Lesions of the extremities tend to present somewhat earlier than retroperitoneal lesions due to easier detectability. L i p o s a r c o m a typically has the gross appearance of a fairly well-circumscribed, lobulated mass [2, 4]. The gross appearance varies according to the histological type and degree o f differentiation of the lesion. The four histologic subtypes of liposarcoma are (1) well-differentiated, (2) myxoid, (3) round cell, and (4) pleomorphic. The myxoid subtype is the most common. The pleomorphic subtype m o s t closely resembles a spindle cell lipoma both clinically and morphologically [2, 17]. The radiological differentiation of a benign lipoma from a liposarcoma can range from difficult to impossible. Plain films typically reveal findings of a nonspecific, soft-tissue mass. CT scanning m a y also be nonspecific, revealing a complex mass of mixed attenuation with soft tissue as well as fatty components. It has been reported that liposarcoma m a y exhibit enhancement following intravenous contrast administration, while lipomas will not enhance [5, 6, 11]. M R I as with CT, m a y be nonspecific depending u p o n the degree of differentiation o f the liposarcoma [6, 13, 14, 17]. In m a n y cases, a biopsy is necessary to secure a definitive diagnosis. The histological analysis in the case described showed a lipomatous
417 mass with focal areas of myxoid change and spindled, fibroblast-like cells. This appearance was m o s t compatible with the diagnosis of spindle cell lipoma. The most interesting aspect of this case is the extensive infiltration and erosion o f the bones adjacent to the mass. Spindle cell lipomas are typically well-circumscribed, less c o m m o n l y encapsulated, and have been shown to be locally infiltrative [8, 12]. The extensive degree of destruction observed in this case is much m o r e c o m m o n l y present in an aggressive, malignant lesion such as a liposarcoma and has not been previously described with a benign lesion such as spindle cell tipoma. The benign nature of spindle cell lipoma requires only conservative treatment. No further intervention was undertaken in this case, and the patient will be followed closely in the future. In summary, we present an unusual case o f spindle cell lipoma of the foot which produced marked bone erosion. Spindle cell lipoma was initially described in the mid-1970s [7] as having the characteristics of a lip o m a with partial or total replacement of mature fat by collagen-forming spindle cells. This lesion is m o s t c o m m o n l y found in the subcutaneous tissue of the posterior neck and shoulder in men between 45 and 65 years o f age [8].
References 1. Angervall L, Dahl I, Kindbloom LG, et al (1976) Spindle cell lipoma. Acta Pathol Microbiol Scand [A] 84:477 2. Azumi N, Curtis J, Kempson RL, et al (1987) Atypical and malignant neoplasms showing lipomatous differentiation. Am J Surg Pathol 11(3): 161 3. Bolen JW, Thorning D (1981) Spindle cell lipoma: a clinical, light and electron microscopical study. Am J Surg Pathol 5:435
4. Bush CH, Spanier SS, Gillespy T (1988) Imaging of atypical lipomas of the extremities: a report of three cases. Skeletal Radiol 17:472 5. Desantos LA, Goldstein HM, Murray JA, et al (1978) Computed tomography in the evaluation of musculoskeletal neoplasms. Radiology 128:89 6. Dooms GC, Hricak H, Sollitto RA, et al (1985) Lipomatous tumors and tumors with fatty component: MR imaging potential and comparison of MR and CT results. Radiology 157 :479 7. Enzinger FM, Harvey DA (1975) Spindle cell lipoma. Cancer 36:1852 8. Enzinger FM, Weiss SW (1988) Soft tissue tumors. C.V. Mosby, St. Louis, p 211 9. Evans HL (1979) Liposarcoma: a study of 55 cases with a reassessment of its classification. Am J Surg Pathol 3 : 507 10. Evans HL, Soule EH, Winkelmann RK (1979) Atypical lipoma, atypical intramuscular lipoma and well differentiated retroperitoneal liposarcoma. Cancer 43 : 574 11. Hunter JC, Johnston WH, Genant HK (1979) Computed tomography evaluation of fatty tumors of the somatic soft tissues: clinical utility and radiographicpathologic correlation. Skeletal Radiol 4:79 12. Kitano M, Enjoji M, Iwasaki H (1979) Spindle cell lipoma - clinicopathologic analysis of twelve cases. Acta Pathol Jpn 29(6): 891 13. Kransdorf M J, Jelinek JS, Moser RP, et al (1989) Soft tissue masses: diagnosis using MR imaging. AJR 153:541 14. London J, Kim EE, Wallace S, et al (1989) MR imaging of liposarcomas: correlation of MR features and histology. J Comput Assist Tomogr 15:832 15. Robb JA, Jones RA (1982) Spindle cell lipoma in a perianal location. Hum Pathol 13(11): 1052 16. Sund S, Hordvik M, Maehle B, etal (1988) Large intramuscular spindle cell lipoma. APMIS 96:347 17. Sundaram M, Baran G, Merenda G, et al (1990) Myxoid liposarcoma: magnetic resonance imaging appearances with clinical and histologic correlation. Skeletal Radiol 19: 359 18. Toker C, Tank CK, Whitely JF, et al (1981) Benign spindle cell breast tumor. Cancer 48 : 1615
Skeletal Radiology
Case report 751 I.J. Braunschweig, M.D. 1, I.H. Stein, M.D. 1, M.I.M. Dodwad, M.D. 2, A.F. Rangwala, M.D. 2, and A. Lopano, M.D. 3 Departments of 1 Radiology, 2 Pathology, and 3 Orthopedic Surgery, Monmouth Medical Center, Long Branch, New Jersey, USA
Imaging studies Fig. 1. AP projection of the left foot reveals marked erosion of the 2nd, 3rd, and 4th metatarsals. Lucency is noted throughout the soft tissues, which represents the lipomatous mass Fig. 2. Axial CT image reveals a large, well-circumscribed, but lobulated soft-tissue mass of low attenuation (--107 to --111 H.U,). Marked erosion of the metatarsals adjacent to the mass is noted
Address reprint requests to. l.J. Braunschweig, M.D., Department of Radiology, Monmouth Medical Ccnter, Long Branch, NJ 07740, USA
9 1992 International Skeletal Society
I.J. Braunschweig et al. : Case report 75l
415 Clinical information
Fig. 3. Tl-weighted axial image reveals a lobulated mass of increased signal in the metatarsal region with extensive deformity of the adjacent bones Fig. 4. Axial T2-weighted image reveals a mass of slightly less signal than seen on TI yet greater than adjacent muscle tissue
A 73-year-old w o m a n was admitted to our institution with a fracture of the proximal area of the right humerus following a fall, which necessitated open reduction. Initial physical examination revealed a palpable, soft mass on the dorsum of the left foot. The patient stated that the mass had been present for m a n y years without significant change. Following surgical repair of the fractured humerus, work-up of the lesion of the left foot proceeded. Plain films, CT and M R I of the left foot revealed a lobulated soft-tissue mass with marked erosion of the 2nd, 3rd, and 4th metatarsals (Fig. 1). A C T scan showed the mass to be of fat attenuation, ranging from - 1 0 7 to - 1 1 1 Hounsfield Units (Fig. 2). M R I revealed a lobulated mass of increased signal on T I (Fig. 3). T2-weighted images demonstrated a mass of slightly less signal than that noted on T I yet still greater than adjacent muscle tissue (Fig. 4). Although the mass appeared to be a well-circumscribed, lipomatous lesion, the uncharacteristically extensive degree of bone erosion necessitated an incisional biopsy.
416
Diagnosis: Spindle cell lipoma causing marked bone erosion Histological examination of the tissue specimens revealed benign adipose tissue in a lobulated pattern, admixed with regions of myxoid tissue with a proliferation of spindle cells. Minimal cellular pleomorphism and increased vascularity were identified. The lesion was seen to infiltrate into adjacent bone, with erosion of the cortex (Figs. 5-7).
Discussion Prior to its initial description in the literature, spindle cell lipoma was frequently misdiagnosed as liposarcoma [9, 10]. The present case provided a similar diagnostic dilemma. Spindle cell lipoma typically is encountered in men between the ages of 45 and 65 years. This tumor has most frequently been found in the subcutaneous tissues of the posterior segments of the neck and shoulder, although various other presentations have been described [1, 12, 15, 16, 18]. These tumors are painless, slowly growing and often present for years and have the potential to infiltrate into adjacent tissue. Histological diagnosis of spindle cell lipoma is based upon the homogeneous relationship of spindle cells to the collagen fibrils and the absence of lipoblasts [3, 8]. Liposarcoma is the second most c o m m o n soft-tissue sarcoma encountered in the adult population [2].
Histology studies 1 Fig. 5. Spindle cell lipoma shows a mixture of mature fat cells with uniform spindle cells. The spindle cells are associated with a mucoid matrix. An increase in the amount of collagen is present. (H & E, x 140) Fig. 6. The spindle cell lipomatous mass infiltrates into the adjacent bony tissue (low power magnification). (H & E, x 100) Fig. 7. Low power magnification shows another area with destruction and erosion of bone by spindle cell lipoma. (H & E, x 100) 1 Diagnosis concurred by Sharon W. Weiss, M.D., Director of Anatomical Pathology, University of Michigan Medical Center, Ann Arbor, Michigan
I.J. Braunschweig et al. : Case report 751
I.J. Braunschweig et al. : Case report 751 Most patients with liposarcomas present in the 5th and 6th decades (similar to spindle cell lipoma). Liposarcomas are usually found in the extremities (most c o m m o n l y the thigh) and the retroperitoneum. Liposarcom a is very rarely seen in the distal aspect of the extremities. The majority of patients present with a painless mass; however, a small percentage of patients experience pain and tenderness. Lesions of the extremities tend to present somewhat earlier than retroperitoneal lesions due to easier detectability. L i p o s a r c o m a typically has the gross appearance of a fairly well-circumscribed, lobulated mass [2, 4]. The gross appearance varies according to the histological type and degree o f differentiation of the lesion. The four histologic subtypes of liposarcoma are (1) well-differentiated, (2) myxoid, (3) round cell, and (4) pleomorphic. The myxoid subtype is the most common. The pleomorphic subtype m o s t closely resembles a spindle cell lipoma both clinically and morphologically [2, 17]. The radiological differentiation of a benign lipoma from a liposarcoma can range from difficult to impossible. Plain films typically reveal findings of a nonspecific, soft-tissue mass. CT scanning m a y also be nonspecific, revealing a complex mass of mixed attenuation with soft tissue as well as fatty components. It has been reported that liposarcoma m a y exhibit enhancement following intravenous contrast administration, while lipomas will not enhance [5, 6, 11]. M R I as with CT, m a y be nonspecific depending u p o n the degree of differentiation o f the liposarcoma [6, 13, 14, 17]. In m a n y cases, a biopsy is necessary to secure a definitive diagnosis. The histological analysis in the case described showed a lipomatous
417 mass with focal areas of myxoid change and spindled, fibroblast-like cells. This appearance was m o s t compatible with the diagnosis of spindle cell lipoma. The most interesting aspect of this case is the extensive infiltration and erosion o f the bones adjacent to the mass. Spindle cell lipomas are typically well-circumscribed, less c o m m o n l y encapsulated, and have been shown to be locally infiltrative [8, 12]. The extensive degree of destruction observed in this case is much m o r e c o m m o n l y present in an aggressive, malignant lesion such as a liposarcoma and has not been previously described with a benign lesion such as spindle cell tipoma. The benign nature of spindle cell lipoma requires only conservative treatment. No further intervention was undertaken in this case, and the patient will be followed closely in the future. In summary, we present an unusual case o f spindle cell lipoma of the foot which produced marked bone erosion. Spindle cell lipoma was initially described in the mid-1970s [7] as having the characteristics of a lip o m a with partial or total replacement of mature fat by collagen-forming spindle cells. This lesion is m o s t c o m m o n l y found in the subcutaneous tissue of the posterior neck and shoulder in men between 45 and 65 years o f age [8].
References 1. Angervall L, Dahl I, Kindbloom LG, et al (1976) Spindle cell lipoma. Acta Pathol Microbiol Scand [A] 84:477 2. Azumi N, Curtis J, Kempson RL, et al (1987) Atypical and malignant neoplasms showing lipomatous differentiation. Am J Surg Pathol 11(3): 161 3. Bolen JW, Thorning D (1981) Spindle cell lipoma: a clinical, light and electron microscopical study. Am J Surg Pathol 5:435
4. Bush CH, Spanier SS, Gillespy T (1988) Imaging of atypical lipomas of the extremities: a report of three cases. Skeletal Radiol 17:472 5. Desantos LA, Goldstein HM, Murray JA, et al (1978) Computed tomography in the evaluation of musculoskeletal neoplasms. Radiology 128:89 6. Dooms GC, Hricak H, Sollitto RA, et al (1985) Lipomatous tumors and tumors with fatty component: MR imaging potential and comparison of MR and CT results. Radiology 157 :479 7. Enzinger FM, Harvey DA (1975) Spindle cell lipoma. Cancer 36:1852 8. Enzinger FM, Weiss SW (1988) Soft tissue tumors. C.V. Mosby, St. Louis, p 211 9. Evans HL (1979) Liposarcoma: a study of 55 cases with a reassessment of its classification. Am J Surg Pathol 3 : 507 10. Evans HL, Soule EH, Winkelmann RK (1979) Atypical lipoma, atypical intramuscular lipoma and well differentiated retroperitoneal liposarcoma. Cancer 43 : 574 11. Hunter JC, Johnston WH, Genant HK (1979) Computed tomography evaluation of fatty tumors of the somatic soft tissues: clinical utility and radiographicpathologic correlation. Skeletal Radiol 4:79 12. Kitano M, Enjoji M, Iwasaki H (1979) Spindle cell lipoma - clinicopathologic analysis of twelve cases. Acta Pathol Jpn 29(6): 891 13. Kransdorf M J, Jelinek JS, Moser RP, et al (1989) Soft tissue masses: diagnosis using MR imaging. AJR 153:541 14. London J, Kim EE, Wallace S, et al (1989) MR imaging of liposarcomas: correlation of MR features and histology. J Comput Assist Tomogr 15:832 15. Robb JA, Jones RA (1982) Spindle cell lipoma in a perianal location. Hum Pathol 13(11): 1052 16. Sund S, Hordvik M, Maehle B, etal (1988) Large intramuscular spindle cell lipoma. APMIS 96:347 17. Sundaram M, Baran G, Merenda G, et al (1990) Myxoid liposarcoma: magnetic resonance imaging appearances with clinical and histologic correlation. Skeletal Radiol 19: 359 18. Toker C, Tank CK, Whitely JF, et al (1981) Benign spindle cell breast tumor. Cancer 48 : 1615
