Solitary fibrous tumours (SFT) were originally identified in the pleura and occur in more than 90% of cases. In recent years, it has been gradually recognized that solitary fibrous tumours can occur in a wide range of locations, with rare cases occurring in the neck and limbs. Since Hanau CA [1] first reported Solitary fibrous tumours SFT in 1995, there have been 10 documented cases of isolated fibrous tumours of the parotid gland, which have not yet been reported in China. Therefore, by analyzing the clinical manifestations, biological behavior and pathological manifestations of this rare disease, corresponding diagnostic and therapeutic principles can be derived to help clinical work.
I. Case presentation
The patient was a 64-year-old male who was admitted to the hospital on 2004-3-12 with the primary cause of a painless swelling under the left earlobe for 13 years. On March 8, 2004, the patient went to a hospital in Beijing, but the diagnosis was not clear. For further treatment, he came to our hospital on March 11, 2004, and was admitted with “left parotid gland swelling”. Since the onset of the disease, he occasionally felt dry mouth, but had no night sweats, cough or fatigue. He had good mental health, diet and sleep, and normal bowel movements.
Past history: He was physically fit and had no history of chronic diseases such as diabetes mellitus, renal disease, or gastric disease, and denied any history of infectious diseases such as hepatitis or tuberculosis. In 1979, he underwent appendicitis surgery in the first division hospital of the guard, and had chronic rhinitis for many years. No history of traumatic bleeding, no history of drug or food allergy. Personal history: originally grew up, now a professional cadre, no history of exposure to epidemic water, radioactive materials, chemical toxins, history of vaccination is unknown. No history of blood transfusion and drug use. Wife is healthy, has 2 sons and 1 daughter, both healthy, no bad habits. Family history: father died in 1970 due to esophageal cancer, mother is alive. He denied any family history of similar diseases or hereditary diseases.
On admission: general condition was good, no abnormalities in the heart, lungs and abdomen. Specialized examination: left-right asymmetry of the maxillofacial region, the left parotid gland was obviously bulging below the earlobe, with a palpable swelling of about 6.0×5.0×2.5 cm in size, normal skin color on the surface, low skin temperature, smooth to palpation, well-defined, active, medium quality, no pressure pain, and no adhesion to the skin. Bilateral temporomandibular joint area had no redness, swelling, and pressure pain, and the opening degree of mouth opening type was normal. Intraoral examination of the jaw relationship was normal. There was no redness or swelling of the parotid ducts, no abnormal secretions, no redness of the pharynx, no large tonsils, and the uvula was in the middle. No enlarged lymph nodes were palpated in the submandibular and cervical areas bilaterally. Preliminary diagnosis after admission: left parotid swelling: 1, pleomorphic adenoma; 2, adenolymphoma.
After admission, routine examination of blood, urine and stool, blood biochemistry, thrombosis, serum microbiological examination, electrocardiogram and chest X-ray showed no abnormalities. Ultrasonography showed a cystic solid mass of about 5.0×3.1 cm in the left parotid area, with clear borders and heterogeneous internal echogenicity; the cystic part was about 2.9×1.8 cm in size, with clear borders and no blood flow signal, while the solid part showed rich blood flow signal. The diagnosis: cystic-solid mixed lesion of the left parotid gland, leaning on the consideration of mixed tumor.
After adequate preoperative preparation, the left facial nerve dissection, left parotid mass and parotidectomy were performed on 2004-3-18 under general anesthesia, and after successful general anesthesia, a routine disinfection sheet was laid, and a conventional “S” shaped incision was made under the lower jaw from the front of the ear screen around the earlobe. The skin flap was peeled forward to the anterior border of the parotid gland and backward to the anterior border of the sternocleidomastoid muscle. The facial nerve was found at the anterior border of the parotid gland, about 1 cm above the angle of the mandible, and then traced and separated along the mandibular border branch to find the common trunk of the facial nerve and the rest of the branches. The envelope was intact, hard, nodular and smooth. Intraoperative freezing reported a spindle cell tumor (left parotid) with a high probability of myoepithelial tumor. Postoperative symptomatic treatment.
The final postoperative pathological results: one piece of tissue was delivered intraoperatively, measuring about 5.0×4.0×3.0 cm, with a gray-white cut surface and local gray-red color, and the gray-red area was 2.5×1.8×1.8 cm in size, clearly defined with the gray-white area, soft in texture, and with an intact envelope. Diagnosis: (left parotid gland) Spindle cell tumor with hemangioepithelioma-like structure in some areas, active cell growth and marked fibrous tissue hyperplasia with vitreous changes in some areas (Figure 1). Immunohistochemistry (Figure 2): CD34 (+), Vim (+), SMA (-), S-100 (-), EMA (-), FⅧ (-), CK (-). Consistent with isolated fibroma. Final diagnosis: isolated fibroma of the left parotid gland. The patient was discharged from the hospital on 2004-3-30.
II. Diagnostic and treatment thinking process
The differential diagnosis of a swelling in the parotid area is highly representative in clinical practice and usually has the following possibilities.
1. Specific inflammation
(1) Lymphatic tuberculosis Tuberculosis of the lymph nodes around the parotid gland (e.g. in front of the ear) and in the parotid gland, without obvious conscious symptoms, can be found as a lump, well-defined, mostly movable, single or multiple, sometimes with ipsilateral or bilateral lymph node enlargement (tuberculosis), and tuberculous lymphadenitis is generally ineffective with antibiotics. It is easily misdiagnosed as a parotid tumor. It can be considered with reference to the presence or absence of tuberculosis, physical signs and other organs, history of tuberculosis, etc. It is also confirmed to be lymphatic tuberculosis after surgical removal of “parotid tumor”.
(2) Actinomycosis Prevalent in the parotid occlusal area, chronic and subacute inflammatory manifestations, long duration, diffuse swelling, unclear boundaries, hard, general dose of antibiotics is ineffective, later can be partially softened, purulent, and the formation of pus fistula, pus is thin, pay attention to the pus in the “sulfur particles”, send smear examination actinomycete mycelium. Inflammatory granulation tissue around the fistula can be taken for pathological examination to confirm the diagnosis.
2. Cysts
(1) parotid cyst No conscious symptoms, soft progressive mass in the parotid gland, soft, non-compressible, postural changes (-), sometimes with fluctuating sensation. ultrasound examination for single or multiple rooms, with liquid flat segments, puncture can be extracted from the cystic fluid, smear for cholesterol crystals.
(2) Sebaceous gland cysts are caused by blockage of the sebaceous gland orifice and are adherent to the skin but not to the subcutaneous tissues, and a small spot is common in the middle of the swelling. It is often combined with infection or septicemia.
3.Benign tumor
They grow slowly, without any conscious symptoms, and are often discovered unintentionally.
(1) Parotid pleomorphic adenoma
Painless progressive parotid mass, often centered on the earlobe, solid, well-defined, spherical or oval, smooth surface or nodular, moderately hard, movable, no pressure pain, no facial paralysis, ultrasound examination, no biopsy, fine needle aspiration cytology examination if available.
(2) Other benign parotid tumors
Warthin tumor is also known as papillary lymphocystic adenoma. Adenolymphoma is usually found in women over 50 years old, mostly in the caudal lobe of the parotid gland, and can occur on both sides, with clear boundaries and softness, and the volume is usually not very large.
(3) Cystic lymphadenoma, also known as cystic hydatid tumor
It is congenital, infantile onset, asymptomatic, soft, progressive swelling, no clear boundaries, usually in the lateral part of the face or neck, transillumination test (+), ultrasound: multifocal cystic. Lymphatic fluid is present on puncture, thin and clear, coagulable, and lymphocytes are visible on smear.
(4) Hemangioma
Congenital, infantile onset, asymptomatic, soft, progressive swelling, no clear boundaries, usually in the lateral part of the face or in the parotid gland, color may change: cyan, blue, purple. Compressibility, postural test (+), ultrasound, venous blood on puncture.
(5) Neurofibroma, congenital, infantile onset, asymptomatic, soft, progressive swelling, no clear boundaries, loose skin, facial deformity, light brown spots or milk coffee spots on the skin of the surface of the mass or other parts of the body, subcutaneous can be found in the form of cords or nodules, there may be pressure pain, thickened nerve fibers, multiple nodules may be distributed along the subcutaneous nerve, into a candelabra, or into a plexiform The diagnosis can be confirmed without biopsy. The diagnosis can be made without biopsy. Initially, only localized swelling and no skin relaxation is present, and the diagnosis is made by pigmentation.
(6) Nerve sheath tumor mostly comes from vagus nerve or sympathetic nerve, with long course; the tumor is a single oval mass, tough, painless, with clear border and no adhesion with surrounding tissues; the movement is large from left to right and small from up to down; some arterial pulsation can be palpated on the surface of the mass, which is due to conduction; there is no murmur on auscultation; blood non-coagulated fluid can be extracted by puncture. The typical Horner’s syndrome may appear if the tumor originates from sympathetic nerve or compresses sympathetic nerve: ipsilateral pupil narrowing, ptosis, eye fissure becoming smaller, conjunctival congestion, facial flushing, auricular redness, dry and sweatless facial skin, nasal mucosa congestion, nasal congestion, etc. IV Malignant tumor
3.Parotid malignant tumor
There are 12 types of malignant tumors in parotid gland, including low grade, moderate grade and highly malignant. There are 12 types of parotid malignant tumors, including low, moderate and high malignancy, which can have different degrees of conscious symptoms and signs, such as pain, facial paralysis and fast growth. They can have different degrees of conscious symptoms and signs, such as pain, facial paralysis and fast growth rate.
The most common ones are mucinous epidermis-like carcinoma and adenoid cystic carcinoma. Mucinous epidermoid carcinoma is divided into two types: highly differentiated and poorly differentiated, the former is of low malignancy and the latter is of high malignancy with indistinct boundaries, hardness, hidden pain or partial facial paralysis, and high rate of cervical lymphatic metastasis.
Adenoid cystic carcinoma, initially behaves like a benign tumor, but this tumor is locally invasive, especially along the neurovascular bundle expansion. It is not easy to cut and recur in surgery, and lung metastasis can occur, and it can survive with tumor for a period of rg.
The carcinoma in pleomorphic adenoma or carcinoma in pleomorphic adenoma can be primary or secondary, the latter is transformed from pleomorphic adenoma and has a history of benign tumors, carcinosarcoma is one of the subtypes and is a truly malignant mixed tumor with rapid development and poor prognosis. Among the highly malignant parotid tumors are adenocarcinoma of the parotid gland. The common features of these tumors are fast growth, obvious conscious symptoms or facial paralysis, etc. All the above tumors need to be diagnosed by pathological examination, but it is generally not advocated to make biopsy before surgery, but to make frozen section during surgery.
4.Other masses
(1) Benign lymphoepithelial lesions
Clinically known as Mikulicz’s disease (Poland, 1888), or Scheglin’s (Sweden, 1933) syndrome, the main manifestations: 1. parotid enlargement, unilateral, often bilateral, individual with enlargement of the submandibular gland and lacrimal gland; 2. dry symptoms:. Dry mouth and eyes. Dry throat. 3. rheumatoid factor may be positive; 4. autoimmune and antinuclear antibodies, anti parotid duct epithelial antibodies are positive; 5. technetium 99 ECT examination parotid gland secretion function is poor. It can be examined by ultrasound, parotid iodine oil imaging, and biopsy of small salivary glands in the medial mucosa of the lower lip.
(2) Erythropoietic lymphogranuloma
It was first found in China, and then in Southeast Asian countries, but has not been reported in Europe and the United States. It develops mainly in males and rarely in females.
The skin is itchy, scratchy or rough, and the peripheral superficial lymph nodes, especially the elbow lymph nodes, may be enlarged. On examination of peripheral blood, the eosinophil count is significantly higher (normal 0-2%) and its absolute count is also significantly higher (normal 50-300/cm3), the amount of which reflects the progressive status of the disease. Biopsy can be done to confirm the diagnosis. This disease has a good prognosis and is sensitive to radiotherapy (20GY), and can also be treated with prednisone.
(4) Bite muscle hypertrophy
On one side or both sides, the enlarged part is the occlusal muscle, and the mass is hard when clenching the teeth, and usually the mass becomes soft, making the lateral side of the lower face square.
From theoretical analysis, inflammatory swelling should be easily distinguished from tumor, i.e. diagnosis of parotid tumor is easier. The reasons for misdiagnosis are: ① patients with inflammatory masses do not have typical clinical manifestations; ② inflammatory masses are not effective or even ineffective in anti-inflammatory (or anti-TB) treatment (clinical observation); ③ inflammatory masses can also show painless, slow-growing tumor growth characteristics, and even the so-called “recent growth acceleration” phenomenon; ④ long-term inflammatory reaction of the parotid gland, which can show the phenomenon of “recent growth acceleration”; ④ inflammation of the parotid gland. The inflammatory reaction of the parotid gland over a long period of time may show the phenomenon of adhesions, fixed masses and nodules (such as tuberculosis) with slightly clear or indistinct circumference; ⑤ the lymph nodes in the parotid gland are not easy to identify due to the masticatory membrane of the parotid gland; ⑥ inflammatory masses that remain after long-term drug treatment are rare clinically; ⑦ clinicians ignore the tendency of lymphocytes to increase, suggesting that the patient may be suffering from a chronic infectious disease, which is often not increased in treated cases. In this case, the possibility of non-specific inflammation or specific inflammation was basically ruled out, mainly based on the long history, slow onset, gradual growth of the mass, no history of growth, and clear boundaries of the mass, no obvious tuberculosis foci on chest radiography, no history of tuberculosis exposure, and no tuberculosis patients in the family. The surface skin was intact, normal color, skin temperature was not high, general condition was good, various blood tests and biochemical and microbiological tests were not abnormal, body temperature was not high, and local lymph node examination was not abnormal, so the possibility of various inflammatory diseases could be basically excluded.
Non-epithelial tumors of the salivary gland account for 5% of all salivary gland tumors, 90% of which are located in the parotid gland. Among them, fibroma with primary origin in salivary gland is very rare, Seifert reported only one case out of 167 cases of non-epithelial tumor of salivary gland. In the 1991 WHO Histological Classification of Salivary Gland Tumors, fibromas are classified as “other benign mesenchymal tumors” among “non-epithelial tumors. In this classification, there is no specific name for “isolated fibroma” [2]. Isolated fibromas were initially found in the pleura and more than 90% of them occurred in the pleura. In recent years, it has been gradually recognized that isolated fibromas can occur in a wide range of locations, with rare cases occurring in the neck and limbs. Of the 13 cases of isolated fibromas of the head and neck documented in the literature, 10 occurred in the parotid gland, 1 in the submandibular gland, 1 in the sublingual gland, and 1 in the temporal region.
Isolated fibromatous lesions of the parotid gland almost always occur in adults without gender differences, although a case in an 11-year-old female was recently reported [3]. From the limited available information, the clinical course of the tumor appears to be benign, presenting as a slowly growing mass that is difficult to name. Depending on the site affected, isolated fibromas tend to be quite large, bounded and lobulated [4-7]. In the present case, the biological behavior of this tumor is benign, slow-growing, and often unintentionally discovered in the parotid gland, with no obvious conscious symptoms, localized swelling and discomfort, and occasional dry mouth. The tumor was smooth to palpation, well-defined, active, medium in quality, no pressure pain, and no adhesion to the skin. However, we believe that needle aspiration biopsy requires rich experience in cytology and clinical operation, otherwise it is of little value, especially parotid tumors are not advocated for needle aspiration biopsy. Many scholars do not advocate excisional biopsy because it increases the patient’s pain and the chance of spread and implantation. Mller reported that the compliance rate for parotid tumors was only 60%.
Mller reported that the compliance rate of parotid tumors was only 60%. Parotid angiography is valuable for determining the nature and localization of tumors. Since Macriolis applied ultrasound technology to diagnose salivary gland diseases in the early 1970s, there have been many reports on the diagnosis of parotid swelling by B-mode ultrasound (B-ultrasound for short) at home and abroad. The B-mode ultrasound is also useful in diagnosing the growth pattern, size, and cystic and solid occupancy of the tumor. In the case of benign tumors in the parotid area, the ultrasound presentation is round or round-like with clear and smooth borders, uniform internal echogenicity, and enhanced posterior echogenicity, which is related to the dense and uniform arrangement of benign tumor cells, less interstitial space, less hemorrhage and necrosis, and other histopathological changes. The diagnosis of benign tumors with cystic-solid mixed lesions of the parotid gland by ultrasonography generally relies on consideration of pleomorphic adenomas, but their cystic-solid boundaries are often unclear. In this case, the ultrasound of the isolated fibroma showed a cystic-solid mass with a predominantly solid nature, and the boundary between the cystic and solid parts was clear, which was significantly different from that of the pleomorphic adenoma. The cystic portion was consistent with the size of the gray-red area in the gross specimen and had an intact envelope, consistent with a hemangioepithelioma-like structure in part of the area. The solid portion was consistent with a fibroma presentation. Therefore, after the final pathological return, we in turn considered that ultrasound examination of isolated fibromas of the parotid gland is of special interest for the diagnosis of this disease. The main difference is that pleomorphic adenomatosis is not a homogeneous signal on ultrasound, although the findings in the present case are still somewhat different from those previously reported in the literature, i.e., there are two different signals on ultrasound, but unlike pleomorphic adenoma, each of the two signals is homogeneous. In addition, no further CT or MRI examination was performed in this case, but it is known from previous literature that in MRI, the signal intensity of tumor and muscle is the same in T1-weighted, while in T2-weighted the signal intensity of tumor is higher than that of muscle, and the signal intensity of the whole tumor is significantly increased after imaging [8], which has important implications for our future diagnosis of isolated fibroma.
Isolated fibrous tumors have a lobulated appearance in gross specimens and generally have a grayish-white parenchyma in the cut surface. The distinctive histological feature is a significant variation in cellular abundance. Often accompanied by focal areas of dense, even scarred, glassy areas, while morphologically homogeneous, well-differentiated fibroblasts are often interspersed between collagen bundles, and vascular epithelioma-like vessels are frequently seen. The tumor cells showed almost constant positivity for CD34, Bcl-2 and Vim, while S-100, actin (actin), cytokeratin (cytokeratin) and desmin (desmin) were all negative [9-12], and these results contributed to the diagnosis.In our patient, immunohistochemistry: CD34 (+), Vim (+), SMA (-), S -100 (-), EMA (-), FⅧ (-), CK (-) could confirm the diagnosis of isolated fibroma.
In histopathological examination, isolated fibromas need to be differentiated from hemangiopericytomas and pleomorphic adenomas. Hemangiopericytoma was reported in 1942 as a vascular tumor originating from epithelial cells (a vascular peripheral variant of smooth muscle cells) and is characterized mainly by the type of histological structure and the tumor cells surrounding the branching structures. It is inconclusive whether adult-type hemangioepithelioma originates from the vascular ectoderm. Adult-type hemangioepithelioma occurs in middle-aged and older adults, in soft tissues, and presents as a slow-growing deep tissue mass, mainly in the lower extremities and retroperitoneum, with benign tumors that rarely recur. With the advances in immunohistochemical staining, the diagnosis of hemangiopericytoma needs to be confirmed after excluding other lesions, as many tumors can show, at least partially, hemangiopericytoma-like changes, of which, isolated fibromas often show such vascular changes [13]. Therefore, although in this case, some areas showed hemangiopericytoma-like structures with active cell growth, the diagnosis of “isolated fibroma” was confirmed by immunohistochemical staining for CD34(+) and Vim(+).
Isolated fibroma should be distinguished from pleomorphic adenoma with abundant mesenchyme and fasciculated arrangement, the former is mainly from mesenchymal tissue in salivary gland, mainly fibrous connective tissue; the latter is mainly from terminal ductal system in gland, the tumor cell component is mainly ductal epithelial cells and myoepithelial cells, immunohistochemical staining shows positive reaction of glandular epithelial markers, such as: keratin, epithelial membrane antigen (EMA) are positive. The immunohistochemical staining showed positive reactions for glandular epithelial markers such as keratin and epithelial membrane antigen (EMA).
Isolated fibromas occurring in other parts of the body are currently treated by surgical removal, and no recurrence has been reported. The main treatment for parotid tumors is surgical excision. Dissection of the facial nerve is the basic technique to remove parotid tumors. One is the centrifugal method, in which the common trunk of the facial nerve is dissected first and the branches of the facial nerve are traced later; the other is the centripetal method, in which, in contrast to the former, the mandibular marginal branches are sought first. Wang Dazhang et al [16-19] modified the centripetal method. The centripetal method is not only theoretically reasonable, but also simple, reliable and safe in surgical practice. In the surgical treatment of malignant tumors of the parotid gland, the issue of facial nerve debulking is currently highly controversial. The growth of malignant tumor can invade the nerve or adhere to it. If the facial nerve is dissected and preserved intraoperatively, the tumor cells attached to it will lead to recurrence after surgery. Ding Hongcai et al. proposed that freezing the branches of the nerve behind the resection of malignant tumors with liquid oxygen can cause fatal damage to the cancer cells, which finally lose their vitality and die. Although the facial nerve is damaged by freezing, it can still recover its function after a period of time, which can not only cure the tumor but also explore a new way to preserve the main branches and functions of the facial nerve. In this case, because the tumor was located in the deep lobe of the parotid gland and was closely related to the facial nerve, the possibility of pleomorphic adenoma was considered preoperatively, and the results of intraoperative freezing were unclear, so total parotidectomy was performed to preserve the facial nerve. In the future treatment process, isolated fibroma of the parotid gland can adopt the principle of removing the tumor within the normal gland and preserving the facial nerve.
III. Review
The correct or incorrect preoperative diagnosis of parotid swelling is the key to its therapeutic efficacy. Only a preliminary diagnosis can be made through medical history, clinical examination, and even therapeutic diagnosis. It is not a simple addition of several instruments, but should be used selectively according to the condition, and the examination procedure should be developed scientifically. In the author’s opinion, ultrasound examination can be used first to determine whether the tumor is occupying, its size and its nature. Of course, CT examination can also be performed, or IgA in serum can be detected [20-21] (significantly higher than normal in head and neck tumor patients). In conclusion, all means should be used to improve the preoperative diagnosis rate. In addition to surgery as the main method of parotid swelling treatment, for some patients with malignant tumors, it should be paired with preoperative or postoperative chemotherapy, radiotherapy or systemic immune support therapy to consolidate the therapeutic effect. For some patients who have lost the chance of surgery and special pathological types, only radiotherapy or chemotherapy can be used. For some inflammatory masses regular anti-inflammatory or anti-TB treatment is available, not all of which require surgery. For the diagnosis of isolated fibroma of the parotid gland, its preoperative confirmation is very difficult, but the authors, through their own experience, suggest that we must be alert during preoperative ultrasound examination when the results show slight differences from other benign tumors such as conventional pleomorphic adenoma, and CT or MRI examination can be performed if necessary, when enhancement should usually be performed, and there will be different manifestations in different weighting periods, which will help us preoperatively being able to consider isolated fibroids at the time of diagnosis can be of great help. Although in terms of surgical options, this disease is not particularly different from the treatment of ordinary benign parotid tumors such as adenolymphoma, in some cases, such as in this case, if we know about this disease preoperatively and can confirm the diagnosis, the patient’s deep lobe of the parotid gland and part of the superficial lobe of the parotid gland can still be preserved because isolated neofibromas basically rarely recur. Of course, immunohistochemical staining is needed to confirm the final diagnosis of this disease, but we have reason to believe that with further understanding of isolated fibroma of the parotid gland, we can reduce some of the unnecessary losses of such patients and provide better service to patients in the future.