Pleomorphic Lipoma of the Neck in an Infant: A Rare Clinical Entity.

Lipomas are rare in the pediatric age group. A 10-month-old male child presented with an asymptomatic neck mass which was evaluated and excised completely. Histopathology was consistent with pleomorphic lipoma, not previously reported in children.

INTRODUCTION

Neck masses are common in children. They include congenital lesions and their complications. Other masses include lymphadenopathy, vascular, inflammatory, and malignant lesions.[1] Tuberculosis remains another suspect in our part of the world. Lipomas are rare in children and mostly occur in the posterior triangle of the neck.[2] Pleomorphic lipomas are rare variants of spindle cell lipoma occurring in men in the seventh and eight decades.[3] An extensive literature search shows no reported cases in children. We report the first case of pleomorphic lipoma, in the pediatric population to the best of our knowledge.

CASE REPORT

A 10month-old male child was brought to the hospital with a lump on the right side of the neck noticed for the past 3–4 days. There was no history of fever, pain, and loss of appetite. There was no history of any recent viral illness, similar lesions in the family. There was no history of tuberculosis contact. There was no history of hoarseness of voice, dysphagia, or respiratory distress.

On examination, the patient was active, alert, and playful. A 5 cm × 4 cm lump noted in the right lower cervical region which was nontender, firm in consistency, and slight mobile in lateral directions with normal overlying skin. No significant lymphadenopathy was noted elsewhere in the body.

Contrast-enhanced computed tomography neck showed a well-defined heterogeneously enhancing mass measuring 4.3 × 4.5 × 2.7 (CC × AP × TR) in the right posterior triangle of the neck with few hypodense areas within it. Two well-defined intensely enhancing areas are seen along with the inferior-medial aspect of the lesion suggestive of pseudoaneurysm. The lesion was extending from level of C3 to T1 vertebra. Fat planes with the overlying right sternocleidomastoid were reported as lost with external contour bulge. The lesion was abutting and displacing the right internal jugular vein medially and mild chinking. The right common carotid and trachea are displaced to the right. No bony erosions or intraspinal extensions were noted. Mediastinal, chest, and abdominal scans were normal [Figure 1].

Figure 1

Computed tomography scan image sagittal view showing well-defined, heterogeneously enhancing mass measuring 4.3 × 4.5 × 2.7 (CC × AP × TR) in the right posterior triangle of the neck with few hypodense areas within it

Preoperative fine-needle aspiration cytology revealed scant cellularity, with large atypical cells with single to multiple nuclei. The nuclei were lobulated and had multiple prominent nucleoli. The findings were suggestive of undifferentiated malignancy and further excision biopsy was advised.

The patient was taken up for excision of mass under general anesthesia. The right supraclavicular incision was given and the tumor was found to be deep to the cervical fascia. Both heads of sternocleidomastoid were divided and the tumor was excised completely. Hemostasis was achieved and the wound was closed in layers. After a 2 years follow up, the patient is asymptomatic and doing well.

On histopathology, there was a well-encapsulated tumor showing a mixture of the mature adipocytes and spindle cells with a few cystic spaces [Figure 2a and b]. Higher magnification showed multinucleated floret cells and bizarre cells [Figure 2c]. The tumor cells are positive for CD34 immunohistochemically [Figure 2d].

Figure 2

A well-encapsulated tumor (a, ×20) showing admiture of mature adipocytes and spindle cells with a few cystic spaces (b, ×100). Higher magnification showing multinucleated floret cells and bizzare cells, (c, ×400). The tumor cells are positive for CD34 immunohistochemically, (d, ×200)

DISCUSSION

Pleomorphic lipoma was first described by Smookler and Enzinger in 1981, soon after the description of spindle cell lipoma.[45] It may be considered as a variant of the spindle cell lipoma. These tumors are rare, and around 150 have been reported in the literature so far.[6] However, this tumor has always been seen in older men ranging with a median of over 55 years.[3] This is the first case report in the pediatric age group.

Pleomorphic lipoma commonly occurs in the posterior neck, shoulder, and back. Infrequently, it may be seen in the tongue, orbit, palms, and vulva.[4] It typically arises from the subcutis of the neck, as a slow growing mass, which requires an average period of 3.3 years to be diagnosed.[7]

Fine-needle aspiration is a first-line investigation in evaluating subcutaneous lesions in the head and neck. However, pleomorphic lipoma can masquerade as a malignancy on fine-needle aspiration; therefore, histological confirmation should be obtained before definitive therapy.[89]

Although pleomorphic lipoma mimics various soft tissue tumors, it can be recognized or suspected on morphologic grounds. The clue to the diagnosis are: (1) Predominantly located in the subcutis or dermis of the posterior neck, upper back, and shoulders. (2) Variable amount of adult fat, rarely fat-free, and no lipoblasts. (3) Atypical cells ranging from rare to frequent. (4) Bundles of dense rope-like collagen. (5) Possible myxoid stroma. (6) CD34-positivity, usually extensive.[10] In addition, multinucleated giant cells are scattered amid the spindle cells, and their nuclei are radically arranged in a “floret-like” pattern.[23] The spectrum of the histology shows a wide variation and varies from tumor(s) that resembles ordinary lipoma with few spindle cells to tumor that mainly consists of spindle cells with just a few fat cells. Cytologically, spindle cells have single elongated hyperchromatic nuclei and inconspicuous nucleoli, whereas multinucleated giant cells have irregular, hyperchromatic, and significantly atypical nuclei. The mitoses of the two cell types are rare. Some lesions may have extensive myxoid stroma, which can be a dominant feature and pose a diagnostic challenge.

The treatment is surgical excision with clear margins, as simple enucleation may lead to recurrences.

CONCLUSION

Common differential diagnosis of neck masses in children, which include congenital malformations, lymph nodes followed by malignant lesions need to be entertained initially. Pleomorphic lipoma should be kept in mind as a rare differential diagnosis in children. It is a benign pseudosarcomatous soft tissue neoplasm that can mimic various malignancies. The detailed histopathological analysis is required for a diagnosis which prevents disfiguring surgery.

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Conflicts of interest

There are no conflicts of interest.