Abstract
Angiolipomas are either encapsulated or non-encapsulated fatty tumours. They are distinguished from other lipomas by the excessive degree of vascular proliferation and because they are mixed with mature adipocytes. They commonly occur in the trunk and extremities and are rare in the maxillofacial area. Only 36 cases in the head and neck have been reported in the literature. The authors report the first non-infiltrating intramasseterine angiolipoma, and a case of non-infiltrating angiolipoma of the cheek. These tumours appear as homogenous low-density areas on CT with no contrast enhancement. MRI gives better tumour delineation and clear definition of the location and longitudinal extent of the mass. Histopathology demonstrates mature adipose tissue and the proliferation of numerous small branching blood vessels. Management of angiolipomas requires complete surgical excision.
Lipomas are the most common soft-tissue tumours, but they are rare in the head and neck region . Angiolipomas represent 6–17% of all lipomas . Angiolipomas are benign subcutaneous lesions most commonly affecting young male patients in the second or third decades of life . The most frequent site is the forearm (two-third of cases) followed by the trunk and upper arm . Only 36 cases of head and neck angiolipoma are reported in the English literature . The purpose of this paper is to describe two cases of angiolipoma. One of them (Case 1) is the first case of non-infiltrating angiolipoma arising in the masseter muscle reported in the literature. The other (Case 2) is a non-infiltrating angiolipoma of the cheek. The authors present these cases and review the cases reported in the literature.
Case 1
A 58-year-old female with no significant medical history was referred for the evaluation of a tender right cheek mass. Five years ago, she noticed a small mass in the parotid-masseterine area. The mass had gradually increased in size, but had suddenly increased over the last 6 weeks. Over the past few weeks, the mass had become more tender and painful. She was referred with the suspicion of parotid tumour. Physical examination revealed a 2 cm, well-circumscribed, firm and mobile mass, located in the right mandibular angle ( Fig. 1 ). No adhesion to the surrounding tissues or overlying skin changes were found. The flow of saliva and facial nerve function was normal. There was no audible bruit or postural or Valsalva manoeuvre changes in size that suggested a vascular nature. There was no palpable cervical lymphadenopathy.
CT scanning ( Fig. 2 ) showed a 2 cm, well-demarcated, low-intensity and heterogeneous soft-tissue mass in close relationship with the superficial parotid lobe and the posterior edge of the master muscle. Fine-needle aspiration did not yield diagnostic material. An initial differential diagnosis of parotid gland tumour, lipoma and haemangioma was considered.
The mass was excised, performing a superficial parotidectomy and total excision of the mass. The mass was within the masseter muscle, in contact with the ramus of the mandible and with the superficial parotid lobe. It was a thin encapsulated, reddish and bilobulated mass. Lipoma was the initial intraoperative impression. 20 months after surgery, there are no signs of recurrence and the facial nerve function is normal.
Histopathologic examination revealed a non-infiltrating intramuscular angiolipoma. Microscopically ( Fig. 3 ), the tumour was composed of convolutes of thin-walled blood vessels, interlacing bundles of mature adipocytes with a prominent perivascular arrangement and mature adipose tissue. These two components were arranged irregularly and intermingled with each other. A well-demarcated lesion surrounded by an incomplete capsule was seen. Focal minimal infiltration of the mass in the masseter muscle was noticed.
Case 2
A 5-year-old male was admitted for diagnosis and treatment of a lump in the right cheek. The patient had been asymptomatic until 1 year previously, when his parents had noticed a mass in the right cheek increasing in size. His medical history was unremarkable. Physical examination revealed a 2.5 cm, subcutaneous, smooth, well delimited mass, just on the anterior edge of the masseter muscle. The overlying skin was blushed. The mass was freely mobile and was not adherent to skin. The buccal mucosa was normal. The clinical impression was haemangioma.
Magnetic resonance imaging (MRI) ( Fig. 4 ) revealed an oval heterogeneous 27 mm × 12 mm mass in the anterior buccal space, with a mixed pattern of high and low intensity in T1-weighted spin echo. The initial suspicion was a vascular lesion, such as a cavernous haemangioma. Intraoral surgical excision revealed an encapsulated hemorrhagic reddish mass, clearly distinguishable from the normal buccal fat pad.
Microscopically, the tumour was composed of mature fat tissue arranged in irregular lobes, circumscribed by thin fibrous septa and areas of abundant blood vessels. The entire tumour was surrounded by a thin capsule of connective tissue. The diagnosis was non-infiltrating angiolipoma. 24 months after surgery, there are no signs of recurrence.
Case 2
A 5-year-old male was admitted for diagnosis and treatment of a lump in the right cheek. The patient had been asymptomatic until 1 year previously, when his parents had noticed a mass in the right cheek increasing in size. His medical history was unremarkable. Physical examination revealed a 2.5 cm, subcutaneous, smooth, well delimited mass, just on the anterior edge of the masseter muscle. The overlying skin was blushed. The mass was freely mobile and was not adherent to skin. The buccal mucosa was normal. The clinical impression was haemangioma.
Magnetic resonance imaging (MRI) ( Fig. 4 ) revealed an oval heterogeneous 27 mm × 12 mm mass in the anterior buccal space, with a mixed pattern of high and low intensity in T1-weighted spin echo. The initial suspicion was a vascular lesion, such as a cavernous haemangioma. Intraoral surgical excision revealed an encapsulated hemorrhagic reddish mass, clearly distinguishable from the normal buccal fat pad.
Microscopically, the tumour was composed of mature fat tissue arranged in irregular lobes, circumscribed by thin fibrous septa and areas of abundant blood vessels. The entire tumour was surrounded by a thin capsule of connective tissue. The diagnosis was non-infiltrating angiolipoma. 24 months after surgery, there are no signs of recurrence.
Discussion
Lipomas are the most commonly benign tumours originating from the subcutaneous regions of the back and shoulder. Only 16% of lipomas appears in the head and neck . When proliferating blood vessels are present, a diagnosis of angiolipoma can be made. These tumours were originally described by Howard and Helwig in 1960 . In 1966, G onzalez -C russi et al. distinguished between the non-infiltrating and the infiltrating type.
6–17% of lipomas are angiolipomas . Multiple lesions are seen in approximately 70–80% of cases . 5% of these cases are familial but the genetic pattern is unclear; some cases demonstrate autonomic dominant inheritance .
Lin and Lin reviewed 23 angiolipomas and found that the onset was always after puberty, with the average age at onset being 21 years . Howard and Helwig reported that the average age at onset was 17 years. They were the first authors to conduct an investigation of angiolipoma. They reported 288 cases, all of which occurred on the trunk and extremities.
Angiolipomas manifest as small (<4 cm), slowly growing, subcutaneous masses. They are painful or tender to palpation . Pain, nerve deficits and cosmetic deformities can occur with continuous growth of the infiltrating angiolipomas .
Nowadays, prior to biopsy, the diagnosis of lipomatous lesions is enhanced by the availability of CT. CT contrast scans show a central low-density mass (lipomatous component) surrounded by areas of contrast enhancement (vascular component). Although a capsule usually does not appear to surround the mass, often it is easily discerned from the surrounding tissue. A contrast enhanced study shows marked enhancement as a result of its intense vascularity, a study without contrast enhancement shows the homogeneous low attenuation of a typical lipoma . MRI was not performed in the authors’ first case, but it is the most sensitive imaging procedure for excluding invasion of the neighbouring structures . In MRI imaging, angiolipoma appears as homogenous, low-intensity areas of no contrast enhancement and heterogeneous areas of extremely high enhancement. Recent reports have suggested that a high vascular content correlates with a preponderance of hypointense regions on T1-weighted spin echo images .
Angiolipomas can be divided into infiltrating and non-infiltrating types . The non-infiltrating type is the most common. It presents as painless or tender subcutaneous nodules, generally in pubescent patients and is rare before puberty . Non-infiltrating angiolipoma occurs in multiple sites in 79% of cases . Histologically it is encapsulated, and is a mixture of mature adipocytes and a proliferation of thin-walled vascular channels . The treatment of a non-infiltrating angiolipoma is simple excision. These tumours show no tendency to recur .
Infiltrating angiolipomas form a distinctive group of non-encapsulated tumours. They usually appear in patients over 30 years of age and occur in the lower extremities . Only 11 cases of infiltrating angiolipomas of the head and neck have been reported in the literature . The tumours were found ( Table 1 ) in five cases in the neck and once each in the oropharynx , the masseter muscle , the temporal muscle , the chin , the cheek and the mucolabial fold. Poorly or non-encapsulated lesions generally originate in skeletal muscle . Characteristically, mature adipocytes and vessels invade the surrounding tissue, separating and displacing the muscle fibres . They can infiltrate surrounding tissues and lead to muscular pain and neural deficits . Hemangiomas and liposarcomas should be considered for differential diagnosis . Treatment consists of wide surgical excision. Infiltrating angiolipomas have not been found to undergo malignant transformation but there is a recurrence rate of 50% . Angiolipomas of the neck tend to be infiltrative . 6 of 8 reported neck angiolipomas were infiltrative . Lin and Lin described a single case that occurred in the supraclavicular region associated with brachial plexus invasion . Stimpson described a case of infiltrating angiolipoma arising adjacent to the thyroid and invading the strap muscle of the neck .
| Author | Location | Age | Sex | Type |
|---|---|---|---|---|
| W eitzner | Cheek | 4 | Male | Non-infiltrating |
| C ampos | Cheek | 44 | Male | Non-infiltrating |
| S anchez Aniceto | Cheek | 11 | Male | Non-infiltrating |
| A li | Cheek | 13 | Female | Non-infiltrating |
| A lvi | Cheek | 13 | Female | Non-infiltrating |
| C ampos | Cheek | Male | Non-infiltrating | |
| A renaz (2009) | Cheek | 5 | Male | Non-infiltrating |
| P olte | Mandible | 39 | Male | Non-infiltrating |
| L ewis | Mandible | 56 | Female | Non-infiltrating |
| M anganaro | Mandible | 51 | Female | Non-infiltrating |
| K oopmann | Nose | 7 | Male | Non-infiltrating |
| S hohet | Nose | 48 | Female | Non-infiltrating |
| D avis | Hard palate | Male | Non-infiltrating | |
| P utney | Periyugular | Female | Non-infiltrating | |
| B rahney | Tongue | 81 | Female | Non-infiltrating |
| F laggert | Hard palate | 8 | Female | Non-infiltrating |
| F einfield | Eyelid | 3 | Male | Non-infiltrating |
| R eilly | Parotid gland | 0.5 | Female | Non-infiltrating |
| P fannenstiel | Maxillary sinus | 43 | Male | Non-infiltrating |
| A lobid | Parapharyngeal | 47 | Male | Non-infiltrating |
| I da -Y onemochi | Buccal mucosa | 69 | Male | Non-infiltrating |
| P alazzo | Thyroid gland | 74 | Female | Non-infiltrating |
| M esolella | Larynx | 71 | Male | Non-infiltrating |
| A renaz (2008) | Masseter muscle | 58 | Female | Non-infiltrating |
| A lvi | Neck | 11 | Female | Non-infiltrating |
| S aydam | Neck | 28 | Female | Non-infiltrating |
| O zer | Neck | 28 | Female | Infiltrating |
| S timpson | Neck | 56 | Female | Infiltrating |
| L in | Supraclavicular | 25 | Male | Infiltrating |
| A ustin | Supraclavicular | 32 | Male | Infiltrating |
| M atsuoka | Neck | 2 | Female | Infiltrating |
| W eldon -L inne | Occiput | 35 | Male | Infiltrating |
| P uig | Chin | 25 | Female | Infiltrating |
| R ushin | M. masseter | 61 | Female | Infiltrating |
| C assiano | Oropharynx | 58 | Female | Infiltrating |
| S ugiura | Mucolabial fold | 74 | Male | Infiltrating |
| H amakawa | Cheek | 23 | Male | Infiltrating |
| H oeft | M. temporal | 63 | Male | Infiltrating |
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