Intramuscular Angiolipoma

Case presentation: (Prepared by: Lorice Mahfoud, MD)
RD, a 23 year old male patient, previously healthy, presented with a 2
month history of left posterior neck mass. He first noted the mass
around 2 months prior to presentation, as a slowly growing painless
mass. There was no history of associated skin changes, fever,
hoarseness, or upper extremity weakness or numbness. He had no
history of infection or trauma.
On physical exam the patient was found to have a left postero-lateral
neck mass, 5x5 cm, non tender, soft, non mobile, non pulsatile and
well circumscribed. No overlying skin changes were noted and normal
muscle power in upper extremities and normal pulses was found.
A fine needle aspirate was done that was found to be acellular.
A total body PET-CT was done and was negative.
An MRI of the neck revealed a 5x5cm, high signal lesion on T1 and
T2, with heterogenous areas, enhancing on IV contrast.
Fig 1: MRI neck of the patient showing T1-high signal lesion in left posterior
neck, within the neck muscles.
The patient was taken to the operating room where he underwent
resection of the posterior neck mass. The mass was easily resected
from the surrounding tissue.
The patient was discharged home the next day after removing the neck
drain. The pathology revealed intramuscular angiolipoma.
Diagnosis: Intramuscular angiolipoma.
Discussion:
Lipomas are the most common soft-tissue tumors, but the head and
neck region is a rare site of origin (1). Angiolipoma (AL) is a variant of
lipoma, with a prominent vascular component, constituting only 6%17% of all lipomas (2).Twenty AL cases have been reported in the head
and neck region. Of these, only 4 cases have been reported in the neck,
3 of the infiltrative type (75%) (1,3). None of the other sites in the head
and neck were infiltrative (3,4,5). ALs of the neck tend to be infiltrative
in nature. They usually present as painful or tender subcutaneous
masses in young adults. Infiltrating ALs also can lead to muscular
pain and neural deficits (1,3).
Histopathologic characteristics of AL are described as follows:
1. gross evidence of tumor formation with or without a capsule;
2. microscopic evidence of 50% mature lipocytes in the tumor;
3. microscopic evidence of angiomatous proliferation in tumor (1,3).
ALs are divided into infiltrating and noninfiltrating types;
histologically similar both with proliferation of blood vessels and
lipocytes, but the infiltrating type have no identifiable capsule, and
there may be pleomorphism, atypia, or mitotic figures (1,3).
Fig 2: Angiolipoma showing mature adipose tissue with numerous vascular
channels (Hematoxylin and eosin stain, _200) (1).
Differential diagnosis includes: hemangioma, lymphangioma, lipoma,
Kaposi‘s sarcoma, liposarcomas and angiosarcoma (1).
The components of nonfatty regions in angiolipomas are small vessels
and capillaries to a variable degree (6); thus, they have hyposignal
intensity on T1-weighted images, bright signal intensity on T2weighted images, and are well enhanced after infusion of contrast
media. The septa of well-differentiated liposarcoma are composed of
muscle fiber, lipoblasts, vessels, and inflammatory cells; thus, the
signal intensities of nonfatty regions of well-differentiated
liposarcoma have been reported with similar findings to those of
angiolipoma (7). Angiolipomas may be more strongly enhanced than
well-differentiated liposarcomas, however, because of the vascular
structure of angiolipoma.
Treatment of ALs is complete surgical excision. The infiltrating type
can create difficulty in excision, with high recurrence rate. In cases
where adequate resection cannot be obtained, radiation therapy may
be used (1). A case of successful treatment with interferon alfa of a
giant infiltrating angiolipoma also has been reported (8).
References:
1- Enver Ozer, MD, and David E. Schuller, MD, Angiolipoma of the neck
Otolaryngology–Head and Neck Surgery (2006) 135, 643-644
2- Lin JJ, Lin F. Two entities in angiolipoma. A study of 459 cases of lipoma with
review of literature on infiltrating angiolipoma. Cancer 1974;34:720 –7.
3- Alvi A, Garner C, Thomas W. Angiolipoma of the head and neck. J
Otolaryngol 1998;27:100 –3.
4- Alobid I, Benitez P, Berenguer J, et al. Parapharyngeal angiolipoma causing
obstructive sleep apnoea syndrome. Acta Otolaryngol 2004; 124:210 –2.
5- Reilly JS, Kelly DR, Royal SA. Angiolipoma of the parotid: case report and
review. Laryngoscope 1988;98:818 –21.
6-Chew FS, Hudson TM, Hawkins IF. Radiology of infiltrating angiolipoma. AJR
Am J Roentgenol 1980;135:781–7.
7- Jee Young Kim, Jeong Mi Park, Gye Yeon Lim, Kyung Ah Chun, Young Ha
Park, and Jin Young Yoo. Atypical Benign Lipomatous Tumors in the Soft
Tissue: Radiographic and Pathologic Correlation. Journal of Computer Assisted
Tomography 26(6):1063–1068
8-Akyuz C, Emir S, Buyukpamukcu M, et al. Successful treatment with interferon
alfa in infiltrating angiolipoma: a case presenting with Kasabach-Merritt
syndrome. Arch Dis Child 2003;88:67.