|Year : 2020 | Volume
| Issue : 2 | Page : 88-91
Glomus tumor of uncertain malignant potential in the arm of an elderly female – Report of an unusual case
Monal Trisal1, Sabina Khan1, Musharraf Husain2, Mohd Jaseem Hassan1, Nehal Ahmad1, Sujata Jetley1
1 Department of Pathology, Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi, India
2 Department of Surgery, Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi, India
|Date of Submission||07-Aug-2020|
|Date of Decision||07-Sep-2020|
|Date of Acceptance||01-Oct-2020|
|Date of Web Publication||22-Dec-2020|
Prof. Sabina Khan
Department of Pathology, Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi - 110 062
Source of Support: None, Conflict of Interest: None
Malignant glomus tumors (GTs) are very rare, and diagnosis requires consideration of specific histologic criteria based on a combination of criteria such as size of the tumor, degree of nuclear atypia, and the level of mitotic activity. GTs that do not fulfill the histologic criteria for malignancy but show at least one feature other than nuclear atypia should be classified as GT of uncertain malignant potential (GTUMP). We report the case of a 65-year-old female with a slowly progressing soft-tissue swelling in the right lower arm near the elbow joint that was successfully treated through wide surgical excision and histologically diagnosed as a GTUMP. On follow-up after 3 months, there was no evidence of recurrence or metastasis. Malignant GTs and GTUMPs are rare, and the nomenclature and classification of these tumors is controversial. These findings and the difficulty of differential diagnosis in a continuum between benignity and malignancy prompted our report.
Keywords: Glomus tumor of uncertain malignant potential, glomus tumors, mesenchymal tumors
|How to cite this article:|
Trisal M, Khan S, Husain M, Hassan MJ, Ahmad N, Jetley S. Glomus tumor of uncertain malignant potential in the arm of an elderly female – Report of an unusual case. Indian J Dermatopathol Diagn Dermatol 2020;7:88-91
|How to cite this URL:|
Trisal M, Khan S, Husain M, Hassan MJ, Ahmad N, Jetley S. Glomus tumor of uncertain malignant potential in the arm of an elderly female – Report of an unusual case. Indian J Dermatopathol Diagn Dermatol [serial online] 2020 [cited 2021 Jan 17];7:88-91. Available from: https://www.ijdpdd.com/text.asp?2020/7/2/88/304339
| Introduction|| |
Glomus tumors (GTs) are uncommon mesenchymal perivascular tumors accounting for <2% of soft-tissue tumors. They are commonly located in the extremities, particularly in the nail bed.
It is hypothesized to be derived from modified smooth muscle cells of a neuromyoarterial glomus, commonly termed glomus body, which helps in thermoregulation through arteriovenous shunting of blood.
These tumors usually occur in areas rich in glomus bodies such as the subungual regions of digits or the deep dermis of the palm, wrist, and forearm. Cutaneous GTs are typically small (subcentimetric), blue–red nodules associated with localized tenderness, cold sensitivity, and excruciating paroxysmal pain out of proportion to tumor size.
GTs are usually seen in young adults with equal frequency in both sexes except for subungual lesions, which are more common in females. Although frequently found in the skin and superficial soft tissues, GTs may occur in deep soft tissue or visceral locations throughout the body. Deeply seated or visceral GTs present as nonspecific mass. These tumors are mostly benign, with very few cases of atypical/malignant behavior reported in literature. Occasional GTs display atypical features such as large size, deeper location, infiltrative growth, atypical mitotic figures, nuclear pleomorphism, and necrosis. However, frankly malignant GTs are exceedingly rare, with fewer than forty cases described in the literature.
GTs not fulfilling the criteria of malignancy but having at least one atypical feature other than nuclear pleomorphism are labeled as “GT of uncertain malignant potential (GTUMP).” Hereby, we report a rare case of large soft-tissue swelling of the right arm in an elderly female, which was diagnosed histopathologically as GTUMP.
| Case Report|| |
A 65-year-old female presented to our hospital with a swelling in the right lower arm near the elbow joint [Figure 1]a. She noted this swelling 4 years back after a history of trauma. On examination, the swelling was soft to firm, nonmobile, nontender, measuring approximately 4 cm × 3.5 cm. X-ray of the right arm demonstrated a well-demarcated, soft-tissue lesion anterior to the distal shaft of the right humerus with tortuous blood vessels over the swelling and no bony involvement [Figure 1]b. Magnetic resonance imaging of the right arm showed a well-defined avid mass lesion measuring 4.4 (anteroposterior) cm × 6.7 (mediolateral) cm × 8.4 (craniocaudal) cm in the anterior compartment of the arm anterior to the distal humerus displacing the brachialis muscle with multiple arterial collaterals supplying the lesion. The visualized muscle and elbow joint were normal. Features were suggestive of a benign soft-tissue lesion in the anterior compartment of the distal arm, likely arteriovenous malformation. Fine-needle aspiration cytology (FNAC) of the swelling was advised, and cytological findings were suggestive of a benign mesenchymal tumor.
|Figure 1: (a) Clinical photograph of the tumor in the right arm. (b) X-ray of the right arm demonstrating a well-demarcated, soft-tissue lesion anterior to the distal shaft of the right humerus|
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FNAC was followed by trucut biopsy. Sections from biopsy tissues revealed a vascular tumor composed of round cells proliferating around thin- to medium-sized vascular channels lined by endothelium. Mild pleomorphism was seen with irregular, mildly hyperchromatic nuclei and inconspicuous nucleoli. Intranuclear inclusion was seen in some cells, similar to those seen in cytology slides of the same case. Reticulin stain was done as there were many hemangiopericytoma-like areas seen on biopsy and reticulin fibers were seen focally around aggregates of tumor cells, unlike around the individual cells as seen in hemangiopericytoma.
Biopsy was thus suggestive of a vascular tumor of intermediate grade. Based on this, wide excision of the tumor was performed and sent for histopathological examination. Grossly, a single, globular, partly skin-covered tissue was received measuring 9 cm × 5.5 cm × 5 cm [Figure 2]a. On cut section, a solid, well-demarcated, gray tan mass was seen in the deeper tissue measuring 5 cm × 4.7 cm × 3.5 cm. A small tiny cystic space was seen at the periphery measuring 1 cm in diameter. Multiple hemorrhagic foci were seen. The adjacent muscle was unremarkable [Figure 2]b.
|Figure 2: (a) Gross photograph showing a resected surgical specimen of arm tumor with overlying ellipse of skin. (b) Cut surface of the gross specimen showing deeply located, well-circumscribed tumor|
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Histologically, sections showed an encapsulated circumscribed tumor composed of nests and sheets of monotonous rounded cells with distinct cell borders, central round nuclei, and amphophilic to eosinophilic cytoplasm [Figure 3]a. Intranuclear inclusions were seen in many of the tumor cells. Tumor proliferation was seen around many capillary-sized blood vessels, at places exhibiting hemangiopericytoma-like pattern [Figure 3]b. Thick collagenous bands dividing tumor cells into lobules were also noted. The surrounding stroma showed myxoid degeneration and focal hemorrhage. No infiltration into the skeletal muscle was seen.
|Figure 3: (a) Photomicrograph showing an encapsulated circumscribed tumor composed of nests and sheets of monotonous rounded cells with distinct cell borders, central round nuclei, and amphophilic to eosinophilic cytoplasm (H and E, ×10). (b) Photomicrograph showing tumor proliferation around many capillary-sized blood vessels, at places exhibiting hemangiopericytoma-like pattern (H and E, ×40)|
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Occasional mitotic figures were seen. However, no atypical mitosis or necrosis was seen. The margins were free of tumor. The tumor cells showed strong cytoplasmic and membranous positivity for smooth muscle actin (SMA) [Figure 4]a and [Figure 4]b and negative for CD34.
|Figure 4: Immunohistochemical staining of the tumor by smooth muscle actin. (a) Low-power view showing smooth muscle actin immunoreactivity. (b) High-power view showing the tumor cells diffusely and strongly positive for smooth muscle actin|
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Based on histological and immunohistochemistry (IHC) findings, a diagnosis of GT was straightforward. However, as the tumor size was >2 cm with deep subfascial location and absence of other atypical features, a histopathological diagnosis of GTUMP was made. On follow-up after 3 months, there was no evidence of recurrence or metastasis.
| Discussion|| |
GTs are rare mesenchymal pericytic neoplasms composed of cells resembling modified smooth cells of normal glomus body. They mostly occur in the skin or superficial soft tissues, although rare cases occur in deep soft tissue or visceral organs. They have a distinctive morphology, location, and symptoms, however rarely display unusual clinical or histopathological features.
The WHO currently recognizes the following categories of GTs: GT, symplastic GT, GTUMPs, and malignant GT (the WHO Classification of Tumors of Soft Tissue and Bone, 2012). Histopathology of benign GT shows characteristic morphology. However, the histopathological differentials for GTs are wide and include tumors such as carcinoid tumor, solitary fibrous tumor, leiomyoma, leiomyosarcoma, lymphoma, and primitive neuroectodermal tumor. In addition, the differential diagnosis of other painful tumors such as eccrine spiradenoma, hemangioma, and neuroma should be kept in mind while evaluating solitary GTs in hand, leading to diagnostic enigma and posing therapeutic challenge.
Histological distinction between GT and nodular hidradenoma may pose a difficult diagnostic problem as both tumors may show circumscribed aggregates of uniform round to epithelioid cells, a myxoid stroma, and variable number of blood vessels. A helpful feature distinguishing GT from hidradenoma or other adnexal tumors is by intimate localization of glomus cells around blood vessels at the periphery of the tumor and lack of ductular differentiation or mucin production. IHC is also very useful because hidradenomas stain for cytokeratin and epithelial membrane antigen, which glomus cells lack.
Differentiating GT from pericytic tumors such as myopericytoma and myofibromatosis may be difficult and relies on typical clinical presentation and characteristic histologic features. Typical GT consists of more rounded cells with a well-demarcated cell membrane arranged in perivascular growth pattern, whereas myopericytoma and myofibromatosis tend to have larger, little less rounded cells with more cytoplasm and ill defined cell borders.
Symplastic GT is a benign tumor with marked nuclear atypia, but lacks mitotic activity or other atypical features. According to the WHO, the diagnosis of malignant GT should be rendered when the tumor exhibits marked nuclear atypia and increased mitotic activity, or atypical mitotic figures. Tumors not fulfilling the criteria for malignancy but having at least one atypical feature other than nuclear pleomorphism should be labeled as “GTUMP.”
In 2001, Folpe et al. reviewed the criteria for diagnosis of malignancy and proposed an intermediate diagnosis of GTUMPs. GTUMP are exceedingly rare. They are characterized by a lack of metastatic disease and a promising prognosis and possess at least one feature of malignant GT such as high mitotic activity, >2 cm in size, or a deep location.
Although GTs of >2 cm in size and deep location were previously considered “malignant,” subsequent experience suggests that these have uncertain potential. Therefore, in our case too, as the tumor was >2 cm with deep location, without any other atypical feature, it was labeled as GTUMP.
On review of literature, we could find very few published cases of GTUMP, particularly of upper extremity, which was recently reported by Javier et al., a case of GTUMP occurring on the skin of the volar area of the arm of a 56-year-old female.
Given their origin as modified smooth muscle cells, glomus cells demonstrate positivity for immunohistochemical markers such as SMA and calponin, and have abundant pericellular production of Type IV collagen. GT cells express vimentin and usually are variably negative for CD34, desmin, and S-100. In our case also, there was strong SMA positivity by these tumor cells.
Benign GTs are cured by resection and have an excellent prognosis; however, malignant GTs are aggressive with high metastatic potential, resulting in metastasis and/or death in 40% of patients. In general, GTUMP are thought to behave similar to benign GTs, although metastasis and aggressive behavior have rarely been seen.
The diagnosis of GTUMP warrants close clinical follow-up. In our case, given the size, deeper location of the tumor, occasional mitotic activity plus the absence of severe cytologic atypia, and atypical mitotic figures, the diagnosis of GTUMP was made. Complete excision to allow for full pathologic examination is recommended.
| Conclusion|| |
There is a wide continuum of benign versus malignant behavior in GTs, at times creating difficulty in differential diagnosis. Ours is a unique case of GTUMP, which represents a challenging, rare neoplasm occurring in an uncommon deep location that encourages a review of diagnostic criteria for GTUMP. Any GT with uncertain malignant potential should be completely excised, followed by long-term surveillance.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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