| Abstract|| |
Earlier, categorized under low grade malignant fibrous histiocytoma and low grade sarcomas, 'superficial CD34 positive fibroblastic tumor', a newly proposed entity, is a low grade mesenchymal tumor of intermediate malignant potential. Morphological features include monomorphic neoplastic spindle cells arranged in a fascicular to storiform pattern along with sheets of pleomorphic epithelioid cells, and multinucleated giant cells with glassy cytoplasm. Diffuse vimentin and characteristic diffuse CD34 positivity is seen in all cases with few showing focal cytokeratin expression. Rest of the melanocytic and mesenchymal markers are negative. Herein, we present a case of superficial CD34-positive fibroblastic tumor in arm swelling of a 16-year-old female. Differential diagnosis of the same on the basis of morphology as well as immunohistochemistry has also been discussed. This is the first case reported from India to the best of our knowledge.
Keywords: Arm, CD34, fibroblastic, immunohistochemistry, superficial, swelling, tumor
|How to cite this article:|
Sood N, Khandelia BK. Superficial CD34-positive fibroblastic tumor: A new entity; case report and review of literature. Indian J Pathol Microbiol 2017;60:377-80
|How to cite this URL:|
Sood N, Khandelia BK. Superficial CD34-positive fibroblastic tumor: A new entity; case report and review of literature. Indian J Pathol Microbiol [serial online] 2017 [cited 2019 Dec 13];60:377-80. Available from: http://www.ijpmonline.org/text.asp?2017/60/3/377/215393
| Introduction|| |
Superficial CD34-positive fibroblastic tumor, a recently proposed entity is a borderline malignant tumor of mesenchymal origin with characteristic morphological and immunohistochemical features. These tumors have striking pleomorphism, granular to glassy cytoplasm, and low mitotic rate and diffuse CD34 positivity. Most of the cases also show focal cytokeratin (CK) positivity. These tumors were earlier categorised under low grade sarcomas not otherwise specified or low grade malignant fibrous histiocytoma (MFH).,
| Case Report|| |
A 16-year-old girl presented to the surgery outpatient department in our hospital with a history of swelling in the right arm for 2 years. On examination, a 3 cm × 3 cm circumscribed mobile swelling was noted on the posterior aspect of the right arm not fixed to skin. Intraoperatively, the lesion was located subcutaneously in the suprafascial plane. The lesion was excised and sent to pathology laboratory for histopathological examination. Excised specimen was well circumscribed and capsulated measuring 4 cm × 3 cm × 2.5 cm. Cut surface was homogeneous and gray-white [Figure 1]a.
|Figure 1: (a) Encapsulated lesion measuring 4 cm × 3 cm × 2.5 cm. (b) Photomicrograph showing spindle cells and epithelioid cells in storiform and fascicular pattern (H and E, ×100). (c) Encapsulated lesion showing marked pleomorphism and a few multinucleated giant cells (H and E, ×100). (d) Cells with glassy cytoplasm (H and E, ×400). (e) Pleomorphic cells with interspersed inflammatory cells (H and E, ×400)|
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Paraffin-embedded sections were stained with H and E stain and showed an encapsulated tumor. The dual cell population of spindle cells and epithelioid cells was arranged in storiform and fascicular pattern admixed with few multinucleated giant cells. The spindle cells showed moderate to focal marked degree of pleomorphism, coarse chromatin, prominent nucleoli and tapering cytoplasm. Periphery of the lesion showed epithelioid tumor cells with round to oval nuclei; prominent punched out nucleoli and abundant granular to glassy cytoplasm. Multinucleated cells showed similar nuclei and abundant cytoplasm. Focal collections of lymphocytes admixed with plasma cells were seen. In spite of the focal marked pleomorphism, mitotic activity was negligible. Interspersed thin walled arborizing vascular network was noted. Entrapment of collagen or fat was clearly absent and capsule was intact [Figure 1]b,[Figure 1]d,[Figure 1]e. Differential diagnoses considered were undifferentiated pleomorphic sarcoma (UPS), epithelioid sarcoma (ES), epithelioid leiomyosarcoma (ELS), atypical fibroxanthoma (AFX), atypical fibrous histiocytoma (AtFH), solitary reticulohistiocytoma, pleomorphic rhabdomyosarcoma (PRMS), and fibrosarcomas arising in dermatofibrosarcoma protruberans (DFSP) and granular cell tumor.
Immunohistochemistry (IHC) was performed on formalin fixed, paraffin embedded sections. Vimentin (Biocare, RTU, V9) and CD34 (Biocare, RTU, QBEnd/10) were found to be diffusely positive. CK (Dako, RTU, AE1/AE3) was focally positive. Desmin (Biocare, RTU, D33, IgG1/kappa), smooth muscle actin (SMA) (Biocare, RTU, 1A4), myogenin (Biocare, RTU, MyG007, IgG1/kappa), CD99 (Biocare, RTU, HO36-1. 1, IgG1), S-100 (Biocare, RTU, 15E2E2), CD31, epithelial membrane antigen (EMA) (Biocare, RTU, Mc-5, IgG1), and CD1a (Biocare, RTU, CD1a007, IgG1/lambda) were negative. Ki67 index (Biocare, RTU, Mc-5, IgG1) was very low. CD68 was focally positive in occasional large xanthomatous cells and background dendritic cells [Figure 2].
|Figure 2: Immunohistochemistry. (a) Diffuse vimentin positivity (×400). (b) Strong diffuse CD34 positivity (×400). (c) Interspersed inflammatory cells showing leukocyte common antigen positivity (×400). (d) Low Ki67 proliferative index (×400). (e) Desmin negative (×400). (f) Focal cytokeratin positivity (×400). (g) CD68 positive xanthomatous cell (×400)|
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A final diagnosis of superficial CD34-positive fibroblastic tumor (SCD34FT) was given. There was no evidence of local recurrence, lymphadenopathy, or distant metastasis till follow-up for 6 months.
| Discussion|| |
Superficial CD34-positive fibroblastic tumor was first reported in a case series by Carter et al., in 2015 as a mesenchymal neoplasm of borderline malignancy with distinct morphological features of proliferation of spindled to epithelioid cells in fascicular/sheets pattern with striking cellular pleomorphism, but an extremely low mitotic rate with prominent nucleoli intranuclear inclusions, granular to glassy abundant cytoplasm and strong CD34 positivity on IHC. Rich arborizing vascular network was also described as a salient feature. The cells were reported as desmin, SMA, S 100, FLI-1, ERG negative. Co-expression of CK was reported in 68% cases. These features were not described in any other previously described entity. These tumors are seen exclusively in the suprafascial location and do not involve deeper tissues and muscle. Subsequently, an occasional case has been added in the literature. All the cases reported so far have been in the age group of 20-74 years. The present case showed all the above characteristic morphological features except for the intranuclear inclusions. On IHC, this tumor was diffusely positive for vimentin and CD34, focally positive for CK and negative for other soft tissue and melanocytic markers concurring with previously reported cases.,
This entity needs to be differentiated from UPS, ES, ELS, and solitary reticulohistiocytoma, AFX, AtFH, and PRMS on the basis of morphology.
UPS is typically seen in sixth to eighth decade and extremely rare in patients under 20 years of age, the most common site being thigh in the lower extremities followed by upper limb. Morphologically, most commonly these lesions show a combination of pleomorphic and storiform areas with some showing numerous tumor giant cells. However, it shows a high mitotic activity, atypical mitoses, presence of necrosis, and CD34 negativity on IHC, unlike the present case.,
Clinically, ES can present in the age range of 13-80 years, both in superficial and deep location, mainly in axial location. On histological examination, ES shows irregular nodules composed of epithelioid cells merging into spindle cells in a desmoplastic stroma. The tumor cells show abundant deeply eosinophilic cytoplasm, unlike SCD34FT, in which tumor cells have glassy cytoplasm. Although ES presents with necrosis, minimal pleomorphism, a proximal-type variant can show marked atypia and frequent mitosis. On IHC, all cases of ES are positive for CK and EMA whereas only 70% cases of SCD34FT have been found to be positive for CK and negative EMA. Contrary to 100% positivity of CD34 in SCD34FT, ES shows CD34 positivity in more than 50% cases. The present case was negative for EMA. SCD34FT retains expression of SMARCB1 unlike ES, however, could not be done in this case.,,
An ELS of soft tissue is a rare lesion, seen in elderly, showing predominantly epithelioid cells with abundant eosinophilic cytoplasm and focal spindle cell component. However, these lesions are seen more commonly in elderly, stain positive for SMA, and alpha-sarcomeric actin and negative for CD34 unlike the present case.,
Solitary reticulohistiocytoma can present at any age as a dermal nodule and is histologically characterized by proliferation of mononuclear, and occasionally multinuclear, predominantly epithelioid histiocytes with eosinophilic “glassy” cytoplasm and minimal mitotic activity. However, it shows minimal cytological atypia and consistent immunohistochemical expression of CD68 and CD163 and negative expression of CD34, unlike the present case which had only focal expression of CD68.,,
AFX, although morphologically similar to superficial CD34-positive fibroblastic tumor, is located in dermal region, shows a high mitotic rate along with atypical mitosis, and is CD10 positive and CD34 negative, unlike this case.,
Dermatofibroma with monster cells or AtFH, though seen more commonly in the extremities, can also be seen in the subcutaneous region. It shows pleomorphic large multinucleated giant cells (monster cells), in a background of characteristic fibrous histiocytoma. However, it shows high mitotic rate, occasional atypical mitosis and is CD34 negative, unlike the present case.,,
PRMS can present in various locations including extremities, has extensive pleomorphism and multinucleated giant cells and have a low proliferative index. Unlike the present case, these lesions present in deeper tissue (skeletal muscle), have myogenin and MyoD1 positivity and are CD34 negative.,
Fibrosarcomas arising in DFSP shows CD68 positivity in the background dendritic cells and are CD34 positive. An odd positivity in large plump epithelioid/xanthomatous cells in the presence of intense CD34 positivity as in this case does need the effort to rule out fibrosarcoma arising in DFSP. However, superficial location, circumscription, absence of herringbone pattern, and absent mitotic activity helped in ruling it out.
Myxofibrosarcomas clinically present in extremities of older adults and in superficial location, however, morphologically they differ from superficial CD34-positive fibroblastic tumors, as they show myxoid nodules with thick-walled, arborizing vasculature, lack cellular pleomorphism, and present with a much higher mitotic rate and proliferating index.,,
Nuclear features on morphology and lack of S-100 immunoreactivity preclude the diagnosis of granular cell tumor as in this case.
Besides superficial CD34-positive Fibroblastic tumors, CD34 positivity is also seen in pleomorphic hyalinizing angiectatic tumor, DFSP, epithelioid angiosarcoma, epithelioid hemangioendothelioma, ES-like hemangioendothelioma, and solitary fibrous tumor. However, these lesions are distinctly dissimilar from this entity on routine morphology.,
Although CD34 expression is a characteristic hallmark of this entity along with retained expression of SMARCB1 and absence of FLI-1 and ERG, consistent nuclear expression of INI-1, and focal positivity of CK has been emphasized on in subsequent case reports.
This lesion which was initially categorized as low-grade MFH -, an oxymoron, and now can be classified as SCD34FT – a borderline malignancy with a better prognosis.
| Conclusion|| |
We are reporting this case with clinical, histopathological, and immunohistochemical features of a superficial CD34-positive fibroblastic tumor right upper extremity in a young female. This entity has been described recently which was initially categorized as low-grade sarcomas not otherwise classified and low-grade MFH. It has a better prognosis and low recurrence rate.
We would like to thank Dr. A. Verma.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Binit Kumar Khandelia
F302 BPTP Freedom Park Life, Sector 57, Gurgaon - 122 003, Haryana
Source of Support: None, Conflict of Interest: None
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