Ann Thorac Surg 2006;81:1901-1903
© 2006 The Society of Thoracic Surgeons
Case report
Intercostal Neuralgia Caused by a Parosteal Lipoma of the Rib
Hyun Koo Kim, MD, PhD,
Young Ho Choi, MD, PhD
*
,
Yang Hyun Cho, MD,
Young-sang Sohn, MD, PhD,
Hark Jei Kim, MD, PhD
Department of Thoracic and Cardiovascular Surgery, Korea University Medical Center, Seoul, Korea
Accepted for publication May 19, 2005.
* Address correspondence to Dr Choi, 97 Guro-Dong, Guro-Ku, Seoul, 152-703 Korea (Email: kughcs{at}korea.ac.kr).
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Abstract
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Parosteal lipoma is an extremely rare benign tumor that is composed mainly of mature adipose tissue, and it has an intimate relationship to the underlying periosteal bone. We believe that only three cases have been previously reported that have described parosteal lipoma of the rib. Although parosteal lipoma is asymptomatic, motor and sensory function deficits have been reported that were caused by the tumor compressing the neuromuscular bundles in the proximal forearm and the sciatic nerve. We present here an exceedingly rare case of intercostal neuralgia caused by a parosteal lipoma of the rib.
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Introduction
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Parosteal lipoma is a rare benign neoplasm that is mainly composed of mature adipose tissue that has an intimate relationship to the underlying periosteal bone [1]. The incidence of this tumor is 0.3% of all lipomas. The most common locations for this tumor are the femur, proximal radius, humerus, tibia, clavicle, and pelvis [2]. We believe that only three previously reported cases of parosteal lipoma of the rib have been described. We report here on an exceedingly rare case of intercostal neuralgia that was caused by parosteal lipoma of the rib.
A 57-year-old woman was referred to us for a palpable mass of 3 years duration that was located on the left posterior chest wall. The mass had slowly increased in size and was associated with progressive intercostal neuralgia for the past 5 weeks. The patient denied any history of trauma. The physical examination revealed a soft, oval-shaped, fixed mass on the left paravertebral area.
Computed tomographic scan demonstrated a well-defined elongated mass with a fat density signal in the left chest wall from the fifth to the eighth posterior rib levels (Fig 1). The mass was mainly located in posterior paraspinal back muscle layer with a local insinuation into the sixth intercostal space and the intrathoracic region. The outer cortex of the attached sixth rib showed a cauliflower-like osseous lesion protruding into the fatty mass lesion, and the inner rib cortex showed a slight diffuse erosive change.
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Fig 1. Computed tomographic scan demonstrating a fatty mass lesion in the intramuscular layer of the left posterior chest wall at the fifth to eighth rib level with an internal protruding osseous mass-like portion from the sixth rib.
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The operation was performed on the patient through a left posterolateral thoracotomy. The mass was strongly adhered to the underlying sixth rib, and it was displacing the intercostal nerve posteriorly and compressing it. The parietal pleura was opened to examine the inner surface of the rib, which had a hard irregularity, but there was no adhesion to the visceral pleural. The patient underwent en bloc resection of the mass and the left sixth rib. The distance from the resection margin of the rib was 6 cm and 3 cm, respectively.
A final diagnosis of parosteal lipoma was rendered. On gross examination, the mass measured 9 x 6 x 4 cm and was relatively well demarcated, yellowish, homogenous, and soft (Fig 2). Histopathologically, the lesion was composed of mature lipocytes that had an intimate relationship with the periosteum. No cellular atypia or lipoblasts were seen (Fig 3).
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Fig 2. The gross finding shows the relatively well demarcated yellowish homogenous adipose tissue attached to the rib. The mass measured 9 times; 6 x 4 cm.
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Fig 3. Microscopic examination shows the well-circumscribed pedunculated bony proliferation with an overlying mass of mature adipose tissue. (Hematoxylin and eosin; x100.)
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The patient had an uneventful postoperative course and she complained of some minimal wound pain at 2 months after surgery.
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Comment
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Lipoma is a soft tissue tumor, but osseous localization of a lipoma is rare [1]. There are three types of osseous lipomas with respect to their relation to the parent bone: (1) interosseous, (2) cortical, and (3) parosteal. Parosteal lipomas are rare and usually asymptomatic benign lesions consisting of mature adipose tissue that is intimately associated with the periosteum of bone. Since their original description by Seering in 1836, various reviews in the English literature have been published during the years regarding this rare entity [3].
Patients with parosteal lipoma range in age from 40 to 60 years of age, and they usually present with a history of a slow growing, large, painless, and nontender immobile mass that is not fixed to the skin. The most common sites of origin for parosteal lipomas are the femur and the radius [2]. Disturbances in the motor and sensory function of the adjacent nerves may occasionally occur due to local pressure, and this can result in muscle atrophy [4]. In our patient, having intercostals neuralgia, the mass intruded into the intercostal space and this compressed the intercostal neurovascular bundle lying beneath the rib.
On roentgenograms, the most characteristic feature demonstrated is a well-defined fat-containing mass adjacent to the cortical bone, and this is commonly associated with reactive changes in the underlying cortex. On computed tomographic scan, parosteal lipoma usually presents as a well-defined mass almost entirely composed of mature adipose tissue with an osseous excrescence within it or erosion at the attachment of the soft-tissue mass to the subjacent cortex, or both [5]. Computed tomographic scan can also confirm the indolent nature of this lesion by showing the mechanical displacement rather than the invasion of the adjacent structures.
Pathologically the lesion is usually a multi-lobulated yellowish mass composed of mature adipocytes, and it is well encapsulated with a broad base of attachment to the underlying bone [6]. Microscopically, the fat cells of a parosteal lipoma appear histochemically identical to the adipocytes that are found in the subcutaneous tissues [7]. There has been no indication to date that this tumor undergoes malignant degeneration, although minimal cellular pleomorphism may occasionally occur.
The treatment of parosteal lipoma is complete surgical resection. In the case with nerve entrapment, the tumor must be removed before irreversible muscle atrophy occurs so as to maintain function. The nerve must also be separated from the parosteal lipoma and care must be taken to spare it during surgical excision [4]. In our case, the intercostal neuromuscular bundle was secured by carefully dissecting it from the mass. Adequate surgical removal of a parosteal lipoma requires either subperiosteal dissection, an osteotome to separate the lesion from the underlying bone or segmental resection of bone; this is in contrast to the relatively easy dissection for a soft tissue lipoma lying adjacent to bone. Local recurrence is unusual, but it has been reported. There are no reports of malignant transformation.
In summary, we have described an extremely rare case of parosteal lipoma of the rib that induced intercostal neuralgia.
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References
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- Murphey MD, Johnson DL, Bhatia PS, Neff JR, Rosenthal HG, Walker CW. Parosteal lipomaMR imaging characteristics. AJR Am J Roentgenol 1994;162:105-110.[Abstract/Free Full Text]
- Fleming RJ, Alpert M, Garcia A. Parosteal lipoma AJR Am J Roentgenol 1962;87:1075-1084.
- Kawashima A, Magid D, Fishman EK, Hruban RH, Ney DR. Parosteal ossifying lipomaCT and MR findings. J Comput Assist Tomogr 1993;17:147-150.[Medline]
- Fitzgerald A, Anderson W, Hooper G. Posterior interosseous nerve palsy due to parosteal lipoma J Hand Surg 2002;27:535-537.[Medline]
- Imbriaco M, Ignarra R, De Rosa N, Lambiase G, Romano M, Ragozzino A. Parosteal lipoma of the rib. CT findings and pathologic correlation Clin Imaging 2003;27:435-437.[Medline]
- Yu JS, Weis L, Becker W. MR imaging of a parosteal lipoma Clin Imaging 2000;24:15-18.[Medline]
- Miller MD, Ragsdale BD, Sweet DE. Parosteal lipomasa new perspective. Pathology 1992;24:132-139.[Medline]
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January 1, 2009;
87(1):
316 - 318.
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Abstract
Introduction
