Fibromyxoid sarcoma of maxilla

A recurrent mass in the nose can pose diagnostic and therapeutic challenges. Even more so, if it exhibits rapid growth, displays unusual clinical features, is a rare histopathological diagnosis or if the patient is unavailable for regular follow-up. We present a case of a middle-aged retrovirus-positive man who underwent surgical removal of a recurrent nasal mass. Histopathology revealed a diagnosis of low-grade fibromyxoid sarcoma, a rare entity in the sinonasal tract. Immunohistochemistry plays a crucial role in clinching the diagnosis, especially for lesions with fibrous and myxoid components. Early and complete surgical resection diminishes the likelihood of recurrence and metastasis.


INTRODUCTION
ost sinonasal masses present alike. Probable diagnosis may be made with imaging (1) confirmed by biopsy; endoscopic management is sufficient in most instances. Nonetheless, recurrent lesions pose a challenge in management, especially when growth is rapid, clinical features are peculiar, and if the patient is unavailable for regular follow-up.

CASE REPORT
A 47-year-old gentleman, known case of Human Immunodeficiency Virus (HIV) infection (CD4 count 306 and HIV-1 viral load <20 copies/ml), on antiretroviral treatment, presented with left nasal obstruction for two months. Examination revealed a polypoidal mass arising from the left lateral nasal wall, completely occluding the left nasal cavity (Fig. 1). Left total maxillectomy was performed. Histopathological examination showed spindle cell proliferation in sheets, fascicles and myxoid appearance, (Fig. 3A) moderately pleomorphic tumour cells with spindle-shaped hyperchromatic nuclei, small nucleoli and a moderate amount of tapering cytoplasm. Interspersed were many thin-walled blood vessels; stroma was predominantly myxoid to focally collagenous. Infrequent areas of necrosis and atypical mitosis were noted. Immunohistochemistry showed strong positivity for vimentin (Fig. 3B), positivity for CD99 (Fig. 3C) and weak positivity for SMA. The tumour cells showed cytoplasmic positivity for betacatenin and absence of nuclear positivity (Fig. 3D), negative for Bcl-2, p40 and epithelial membrane antigen. All margins except lateral were free of tumour. Clinicoradiopathological and IHC features were correlated, and a diagnosis of low-grade fibromyxoid sarcoma (LGFMS) was considered. The patient was referred to a higher centre for mucin-4 (MUC-4) marker and molecular testing, as they were not offered at our hospital. However, he was lost to follow up. His relatives confirmed that he had not considered any further management and had expired about six months after maxillectomy.

DISCUSSION
Our patient presented with unilateral nasal obstruction and a left-sided nasal mass; clinically, inverted papilloma was regarded the first diagnosis, as it is known to occur as a polypoidal mass, has a high recurrence rate, and causes bone erosion (2). A diagnosis of Kaposi sarcoma or NHL could not be ruled out clinically. While external approaches were once exclusively performed for most of the sinonasal tumours, endoscopic clearance has attained acceptance due to reduced morbidity (2). Since the mass was limited, endoscopic medial maxillectomy was performed on our patient. Unpredictably, histopathological diagnosis favoured pseudosarcomatous myofibroblastic proliferation (PMP), an unusual entity, also considered inflammatory myofibroblastic tumour (IMT), with malignant potential. The lack of typical clinicoradiological characteristics makes preoperative diagnosis difficult (3). It is commoner in the genitourinary tract than the head and neck (submandibular space, maxillary region, oral cavity; 3,4). Steroids and methotrexate have been used with surgery for the successful management of maxillary IMT (5). Unfortunately, they were not considered in our patient owing to his immunocompromised state.
LGFMS is a rare sarcoma with an indolent clinical course affecting the younger population (8). Only a handful of cases have been reported in the head and neck, predominantly mandible and larynx. Due to its rarity, pathologists may not consider LGFMS as a differential; immunohistochemistry is valuable. MUC-4 positivity and molecular testing are confirmatory (9). The unavailability of these tests in our hospital led to a higher centre referral. The patient's unwillingness for further evaluation and the onset of the coronavirus pandemic contributed to his early demise. Wide surgical resection with clear margins is the standard management of LGFMS. It is unlikely to respond to chemoradiation as it is a lowgrade malignancy with a low mitotic rate. Recurrence is 10%, and late metastasis rate is 5% (8).

CONCLUSION
LGFMS is rare in the sinonasal region; it has a prolonged subclinical presentation. IHC plays a crucial role in clinching the diagnosis, especially for lesions with fibrous and myxoid components; this entity must be kept in mind in such cases, enabling early, adequate surgical resection and diminishing the likelihood of recurrence and metastasis.