Benign Spindle Cell Tumor Research Articles

A Case of Solitary Fibrous Tumor in the External Auditory Canal

Solitary fibrous tumor (SFT) is a rare benign spindle-cell neoplasm, most often found in the pleura. Recently, it has been reported to appear throughout the body but rarely in head and neck region. Tumors in the external auditory canal, in particular, have been very rarely reported. We experienced a case of a 55-year-old male with a 6-month history of progressive swelling from the orifice of left external auditory canal. The tumor was round, well circumscribed, almost completely obstructing the left external auditory canal. On the enhanced temporal bone CT and enhanced paranasal sinus MRI, a 2.0×1.7 cm sized mass was observed at the left external auditory canal. He was treated with surgical excision under general anesthesia. Histopathologic examination confirmed the diagnosis of SFT. This case report presents a rare case of a SFT arising in the external auditory canal.

Solitary lung myofibroma in an infant

Abstract Myofibroma is a rare benign spindle cell neoplasm that occurs predominantly in infants and young children. The disease can be classified into solitary and multicentric forms. The solitary form typically affects the skin and subcutaneous tissue while the multicentric form is usually more severe due to the involvement of internal organs. A solitary myofibroma involving the lung is an extremely rare variant of this disease. To the best of our knowledge, this form of the disease has not been well documented in the literature. We report here an 8-month-old male who presented with cough and fever and was found to have a well-circumscribed lesion in his right lung. CT imaging revealed a soft tissue mass with some intratumoral calcification. A systemic examination was unremarkable. Thoracoscopic excision of the mass was successfully performed. Histopathology revealed a spindle cell tumor consistent with the diagnosis of solitary myofibroma. The patient had a stable recovery and was discharged home after 24 hours. There were no recurrences after a follow up period of 1 month.

Pediatric extramammary myofibroblastoma in the head and neck region: a case report

<p>A rare form of mesenchymal neoplasm that typically presents in older men and women is mammary myofibroblastoma. Even so rarely, these benign tumours may occur outside of the breasts in soft tissues; which then are called mammary-type myofibroblastoma. There can be marked variability in the histological composition of these benign spindle cell tumours. Along the milk line is the commonest presentation of these extramammary myofibroblastoma. Here we have an 8 years old female patient presented to the department of otorhinolaryngology with a painless, fusiform swelling over the right lateral aspect of tongue in the past 6 months. Intra oral examination revealed a non-tender, non-ulcerated fusiform shaped mass approximately 3×2 cm firm in consistency arising from the right lateral border of the tongue. FNAC was done which showed spindle cell tumour tongue. The lesion was diagnosed as mammary type myofibroblastoma on immunohistochemistry.</p>

The Value of H3K27me3 Immunohistochemistry in Differentiating Malignant Peripheral Nerve Sheath Tumour with Its Histologic Mimickers.

Background:Diagnosis of malignant peripheral nerve sheath tumor (MPNST) is rather challenging due to its divergent morphologic heterogeneity and lack of specific ancillary test. The emergence of H3K27 trimethylation (H3K27me3) as a new immunohistochemistry (IHC) marker for MPNST have recently available to assist pathologists in differentiating MPNST from other histologic mimics. We aim to study the expression pattern of H3K27me3 in MPNST and its histologic mimickers and their association with the clinicopathological data. Methodology:A total of 59 benign and malignant spindle cell tumours (18 MPNST and 41 of its histologic mimickers which included 10 schwannoma, 13 neurofibroma, 4 synovial sarcoma, 3 fibrosarcoma, 2 gastrointestinal stromal tumour (GIST), 4 leiomyosarcoma, 1 spindle cell liposarcoma, 1 solitary fibrous tumour, 2 low grade fibromyxoid sarcoma and 1 unclassified spindle cell sarcoma), diagnosed from January 1998 to April 2018 in Hospital Universiti Sains Malaysia (HUSM) were tested for H3K27me3 by IHC. The MPNST histological grade was assessed based on the French Fe’de’ ration Nationale des Centres de LutteContre le Cancer (FNCLCC) for 3 tiers system (low grade, intermediate grade and high grade). The clinicopathological data were retrieved from the patients’ record. Results:A total of 61.1% (11/18 MPNST) showed loss of H3K27me3 expression which is statistically significant as compared to its histologic mimics (p<0.001). Similar findings (p=0.026) were also observed in high grade MPNST (81.8%), intermediate grade MPNST (100%) and 0% in low grade MPNST. Conclusion: H3K27me3, combined with other panel of markers, is useful in MPNST diagnosis to differentiate it from the histological mimickers.

29. Angioleiomyoma with a plexiform pattern in the broad ligament – A case report

Background: Angioleiomyoma (ALM) is an uncommon benign mesenchymal neoplasm that originates from smooth muscle cells and contains numerous thick-walled blood vessels. Aim: We are presenting a case report of a rare ALM with a plexiform pattern arising from the broad ligament. Methods: A 46-year-old female presented with lower abdominal pain. US scan revealed bilateral adnexal masses with increased vascularity. The left adnexal mass was 50 mm with internal vascularity. The left adnexal mass, measuring 50×40×20 mm in aggregate revealed a haemorrhagic solid and cystic cut surface with a smooth outer surface. Histology showed a benign spindle cell tumour composed of bland spindle cells arranged in a plexiform pattern. There were many intermingled thick walled blood vessels. Nuclear atypia, increased mitosis and necrotic areas were absent. The tumour cells were strongly positive for SMA, Desmin, ER, PR, focally positive for CD34. The tumour cells were negative for EMA, AE1/AE3, S100 and STAT-6. The diagnosis was ALM with a plexiform pattern likely arising from the broad ligament. The clinical and radiological findings showed normal bilateral ovaries, fallopian tubes and a fibroid uterus. Results and conclusion: ALM is a benign mesenchymal neoplasm commonly found in the skin of extremities and rarely occurs in uterus. The ALM arising from broad ligament is much rarer than the uterine counterpart. There has been only three reported cases of ALM arising from broad ligament after extensive literature review. The patients with uterine and broad ligament angioleiomyomas usually present with abdominal pain which is believed to be related to ischemia due to vascular contraction. It has to be differentiated from the other mesenchymal neoplasms with prominent vascular components and the differential diagnosis includes angiofibroma, angiomyolipoma, angiomyofibroblastoma and perivascular epitheloid tumours. A large broad-ligament lesion can mimic ovarian masses and preoperative imaging and histopathologic confirmation may help in avoiding radical surgery.

Paratesticular Tumors: A Report of Two Rare Cases

Paratesticular tumors are rare comprising 7-10% of total intrascrotal tumors of which 70% are benign and 30% are malignant. Leiomyomas and undifferentiated pleomorphic sarcomas are two such rare paratesticular tumors which should be accurately diagnosed for purpose of treatment and prognosis. We report here two cases. In first case, a 65-year-old man presented with paratesticular mass of 12 years duration. Histology showed features of benign spindle cell tumor. On immunohistochemistry the tumor cells were positive for vimentin, desmin, h-caldesmon and SMA. Based on these findings a diagnosis of leiomyoma of scrotum was made. In second case, a 66-year-old male presented with left paratesticular mass of eight months duration. Histology showed features of high-grade sarcoma. On immunohistochemistry tumor cells were focally positive for SMA and negative for h-caldesmon, desmin, calretinin and ALK-1. A final diagnosis of undifferentiated pleomorphic sarcoma of paratesticular region, grade 3/3 was made.

AGGRESSIVE FIBROMATOSIS IN THE MANDIBULAR ANGLE

Fibromatosis is a benign locally aggressive spindle cell neoplasm that rarely affects the oral and perioral tissues. A 16-year-old adolescent boy was referred because of a swelling in the right mandibular angle lasting 1 month and progressive difficulties in mouth opening lasting 8 months. Regional examination showed a swelling in the right mandibular angle covered by normal skin and limited mouth opening. Panoramic radiograph and computed tomography revealed multilocular radiolucent lesion in the right mandibular angle. Clinical diagnosis included aneurysmal bone cyst, nodular fasciitis, and myxoma. Because of the location of the lesion, it was removed under general anesthesia with per-surgical frozen analysis. Provisional frozen diagnosis was a benign spindle cell neoplasm, and histologic and immunohistochemical analysis of the surgical specimen confirmed the diagnosis of aggressive fibromatosis. The patient has been followed up with no signs of local recurrence. Fibromatosis is a benign locally aggressive spindle cell neoplasm that rarely affects the oral and perioral tissues. A 16-year-old adolescent boy was referred because of a swelling in the right mandibular angle lasting 1 month and progressive difficulties in mouth opening lasting 8 months. Regional examination showed a swelling in the right mandibular angle covered by normal skin and limited mouth opening. Panoramic radiograph and computed tomography revealed multilocular radiolucent lesion in the right mandibular angle. Clinical diagnosis included aneurysmal bone cyst, nodular fasciitis, and myxoma. Because of the location of the lesion, it was removed under general anesthesia with per-surgical frozen analysis. Provisional frozen diagnosis was a benign spindle cell neoplasm, and histologic and immunohistochemical analysis of the surgical specimen confirmed the diagnosis of aggressive fibromatosis. The patient has been followed up with no signs of local recurrence.

Practical approach to diagnosis of bland-looking spindle cell lesions of the breast.

SummaryThe diagnosis of bland-looking spindle cell lesions of the breast is often challenging because there is a close morphological and immunohistochemical overlap among the different entities. The present review will discuss reactive spindle cell nodule/exuberant scar, nodular fasciitis, inflammatory pseudotumor, myofibroblastoma (classic type), lipomatous myofibroblastoma, palisaded myofibroblastoma, benign fibroblastic spindle cell tumor, spindle cell lipoma, fibroma, leiomyoma, solitary fibrous tumor, myxoma, schwannoma/neurofibroma, desmoid-type fibromatosis, dermatofibrosarcoma protuberans, low-grade fibromatosis-like spindle cell carcinoma, inflammatory myofibroblastic tumor and low-grade myofibroblastic sarcoma arising in the breast parenchyma. The pathologist should be aware of each single lesion to achieve a correct diagnosis to ensure patient a correct prognostic information and therapy. Accordingly representative illustrations and morphological/immunohistochemical diagnostic clues will be provided.

Multiple Paratesticular Fibrous Pseudotumors in an Adult Patient: Case Report

Abstract- Paratesticular fibrous pseudotumors (PFP) are relatively rare benign spindle cell tumors. These tumors usually are originated from testicularis tunics and grow into the epididymis and spermatic cord. PFP is a consequent of a reactive proliferation of inflammatory tissue. We report a case of PFP with simultaneous multiple tunica albuginea and tunica vaginalis lesions. A 33-year-old man presented with painless right scrotal lump, normal serum tumor markers, and one centimeter paratesticular mass in ultra-sonography that underwent testis-sparing surgery due to a benign microscopic appearance in frozen section evaluation. Testis sparing surgery can be considered as the preferred management because of the lack of obvious evidence of potential malignancy in this tumor

SOLITARY FIBROUS TUMOR OF BREAST

Solitary fibrous tumours (SFTs) are fibroblastic mesenchymal tumour primarily identified in the pleura but are now being reported in other anatomic sites as well. SFT is generally characterised as a radiologically confined neoplasm composed of a proliferated spindle cells arranged in patternless manner. Intervening tissue shows prominent haemangiopericytoma-like vessels. Stroma is usually fibrous. Tumour is positive for CD34. SFT has a specific translocation representing fusion NAB2 with STAT6 genes. This translocation can be highlighted with very good specificity and sensitivity using STAT6 immunohistochemical stain. Some cases of SFTs have also been described in the breast. Rarely, SFT can show aggressive behaviour. SFT enters the differential diagnoses of benign and malignant spindle cell tumours of breast and it is, therefore, important that its clinical, radiological and pathological features are known to clinicians and diagnosticians. Key words: CD34, myofibroblastoma, NAB2-STAT6, solitary fibrous tumour

SUN-328 Non-Islet Cell Tumor-Induced Hypoglycemia in a Patient with IGF-2 Producing Spindle Cell Neoplasm

Background: Non-islet cell tumor-induced hypoglycemia is a rare paraneoplastic syndrome with approximately 300 reported cases in the literature. Classically these tumors secrete insulin-like growth factor-2 (IGF-2) to induce hypoglycemia, but the etiology and regulation of the hormone secretion remains poorly understood. We present a case of non-islet cell hypoglycemia from a spindle cell neoplasm of the lung, which appeared to show inconsistent secretion of IGF-2. Clinical case: A 72-year-old, non-diabetic male presented with episodes of altered mental status due to hypoglycemia with unintentional weight loss. Blood glucose was 35 mg/dL upon admission. CT chest showed an 18 cm tumor in the left hemithorax. The patient continued to have hypoglycemia throughout his hospital stay. At a time when the serum glucose was 48 mg/dL, a biochemical work up for hypoglycemia showed C-peptide 0.21 ng/mL (0.78-5.19 ng/mL), proinsulin 1.6 pmol/L (0-10 pmol/L), insulin 0.1 U/mL (1.9-23 U/mL), β-hydroxybutyrate 0.1 mmol/L (0-0.4 mmol/L), and a negative sulfonylurea screen. Given the large lung tumor, IGF hormones were measured: IGF-1 59 ng/mL (36-215 ng/mL), IGF-2 670 ng/mL (333-967 ng/mL). While both were within normal ranges, the IGF-2/IGF-1 ratio was 11.35. Biopsy of the lung mass showed benign spindle cell neoplasm, consistent with solitary fibrous tumor. The patient was diagnosed with paraneoplastic non-insulin mediated hypoglycemia and was transferred to our hospital for resection of the lung mass. During the first 96 hours after transfer, the patient had no hypoglycemic episodes and repeat laboratory values showed IGF-1 of 72 ng/mL, IGF-2 of 162 ng/mL, IGF-2/IGF-1 ratio of 2.25 with a glucose of 119 mg/dL, indicating the secretion of IGF-2 may have been intermittent. However, he later developed recurrent hypoglycemia and underwent resection of the tumor. Pathology showed a malignant solitary fibrous tumor. Blood sugars improved within 2 days after tumor resection and patient did not have further hypoglycemia. Discussion: Literature review shows that tumors causing non-islet cell hypoglycemia are large with one-third located in the chest and two-thirds in the retroperitoneum. They can secrete “big” IGF-2, which can activate insulin receptors to inhibit glucose output from the liver and increase uptake in muscle and adipose tissue leading to hypoglycemia. Interestingly, the IGF-2 level is not always outside the normal range, but a ratio of IGF-2/IGF-1 greater than 10 can be another marker of paraneoplastic hypoglycemia. We believe our case is unique in that during a 48-hour period of intense observation, the patient had no hypoglycemia and the IGF-2 levels and IGF-2/IGF-1 ratio decreased to the normal range. Thus, in patients with suspected tumor-mediated hypoglycemia, the IGF levels may need to be drawn during a hypoglycemic event, much like the workup for insulinoma.

STAT6 expression in spindle cell lesions of the breast: An immunohistochemical study of 48 cases

The diagnosis of spindle cell lesions of the breast parenchyma is challenging. Some of these lesions share the expression of CD34, posing differential diagnostic problems, especially in core biopsies. Recently, antibodies against the STAT6 C-terminal, are being used in paraffin-embedded tissues as a surrogate for identifying the NAB2–STA6 fusion gene which is considered a specific molecular marker for solitary fibrous tumor. Accordingly, we investigated the expression of STAT6 in a large series of uncommon spindle cell tumor-like and tumor lesions occurring primarily in the breast parenchyma. We collected 10 classic-type myofibroblastomas, 9 desmoid-type fibromatosis, 6 spindle cell metaplastic carcinoma, 5 benign fibroblastic spindle cell tumors, 3 solitary fibrous tumors, 7 pseudoangiomatous stromal hyperplasias, 2 reactive spindle cell nodules, 1 leiomyoma, 1 spindle cell lipoma, 1 case of inflammatory pseudotumor, 1 nodular fasciitis, 1 myxoma and 1 dermatofibrosarcoma protuberans. A diffuse and strong nuclear STAT6 expression was restricted only to solitary fibrous tumors, while the other lesions were negative or showed only weak cytoplasmic expression. The present study confirms that the demonstration of a diffuse and strong STAT6 nuclear staining is very helpful in distinguishing solitary fibrous tumor from other spindle cell mimics arising in the breast.

Utility of STAT6 and 13q14 deletion in the classification of the benign spindle cell stromal tumors of the breast

The boundaries of the benign spindle cell stromal tumors of the breast are still confusing. This is the reason why different names are interchangeably used for the same tumor and vice versa the same name for different tumors. Therefore, we studied the immunoexpression of easily available markers, such as CD34, α-smooth muscle actin, and desmin, with the addition of STAT6, as well as the chromosome 13q14 region by fluorescence in situ hybridization analysis in a series of 19 cases of benign spindle cell stromal tumors of the breast. Based on the morphologic and immunohistochemical findings, the following histotypes were identified: (i) tumors (10/19 cases) with the characteristic morphology of myofibroblastoma and stained with vimentin, CD34, desmin, and α-smooth muscle actin; (ii) fibroblastic benign spindle cell tumors (5/19 cases) composed of fibroblast-like cells stained only with vimentin and CD34; (iii) tumors (2/19 cases) with the typical morphologic features of solitary fibrous tumor and stained with vimentin, CD34, and STAT6; (iv) 1 case of spindle cell lipoma stained with vimentin and CD34; and (v) 1 case of fibroma composed of a paucicellular, diffusely hyalinized stroma with expression of vimentin and CD34. Notably most of the tumors, with the exception of solitary fibrous tumor, showed monoallelic deletion of FOXO1. This finding supports that myofibroblastoma, fibroblastic benign spindle cell tumor, spindle cell lipoma, and fibroma of the breast are histogenetically related lesions which belong to the same tumor entity.

Desmoplastic melanoma of the oral cavity: diagnostic pitfalls and clinical characteristics.

ObjectivesDesmoplastic melanoma of the oral cavity is an extremely rare condition that is often confused on initial diagnosis with non-melanotic benign lesion or spindle cell tumors. The purpose of this article was to raise awareness of the disease using a literature review.Materials and MethodsWe analyzed 19 desmoplastic melanoma cases reported in the literature and added our experience. Data on clinical, histopathology, treatment, and survival were retrieved and analyzed. Survival analysis was by the Kaplan-Meier method.ResultsInitial clinical and histopathological features were indistinctive, and a definite diagnosis of desmoplastic melanoma at initial assessment was possible in only 23.5% of cases. Among tests, immunohistochemical studies for S-100 and vimentin were all positive. The 5-year disease-free survival rate for oral desmoplastic melanoma was 0%, and the 5-year overall survival rate was 55.0%.ConclusionOral desmoplastic melanoma has a high percentage of initial misdiagnosis and propensity for local recurrence. Thus, careful initial diagnosis and adequate surgery may result in improved overall survival.

Clinicopathologic and molecular genetic characterizations of biphenotypic sinonasal sarcoma

Objective: To investigate the clinicopathologic characteristics, immunophenotypes, molecular genetics, and diagnostic and differential diagnostic features of biphenotypic sinonasal sarcoma (BSNS). Methods: Three cases of BSNS were retrieved, the histomorphology, immunophenotype and molecular genetics were analyzed with review of literature. Results: There were 2 male and 1 female patient aged 45, 29 and 40 years, respectively.Computed tomography and magnetic resonance imaging examinations showed a large polypoid mass occupying the sinonasal cavity in all 3 patients. Microscopically, these tumors were un-circumscribed and composed of cellular spindle-shaped cells arranged in long and interlaced fascicles. A hemangiopericytoma-like growth pattern was frequently identified. The overlying hyperplastic respiratory epithelium invaginated down into the tumor forming a cystic (2 cases), glandular (1 case) structures and inverted in a papilloma-like (1 case)pattern, and foci of eosinophilic metaplasia were also noted in 2 of the three cases. The tumor nuclei were bland-appearing, mitoses were scarce and necrosis was absent. Immunohistochemically, the tumor cells showed co-expression of neural and myogenic markers in all the 3 cases, including that 3/3 showed diffuse and strong positivity of S-100 protein, 3/3 positivity of smooth muscle actin (1 diffuse and 2 focal), 1/2 diffuse positivity of calponin, 1/3 focal positivity of desmin, and 1/1 focal positivity of MyoD1.In addition, 1 detected for β-catenin showed focal nuclear positivity. None of the 3 showed positivity to cytokeratin, CD34 or SOX10 in the tumor cells.Ki-67 showed an index <5%, 10% and <2%, respectively. Fluorescence in situ hybridization analysis showed rearrangements of PAX3 gene in all 3 cases. In case 3, reverse transcription polymerase chain reaction, followed by Sanger sequencing, demonstrated an in-frame fusion between PAX3 and FOXO1.Follow-up information (range 3-15 months)showed no evidence of local recurrence or distant metastasis in three cases. Conclusions: BSNS is a newly described entity which can be readily confused with a variety of benign and malignant spindle cell tumors encountered in the sinonasal cavity; immunohistochemistry co-expression of neural and myogenic markers and PAX3 gene rearrangement can help distinguish this tumor from its many mimickers.

Characterization of CD34-deficient myofibroblastomas of the breast.

Mammary myofibroblastoma is a benign spindle cell tumor that can show variable morphologic patterns and lines of differentiation. Diffuse and strong immunohistochemical expression of CD34 is a characteristic of myofibroblastoma and greatly aids in confirming a diagnosis. Myofibroblastoma has been shown to belong to a family of CD34-positive tumors with similar morphology that show a deletion of 13q14, which includes RB1 and FOXO1A genes. The purpose of this study was to better understand a subset of myofibroblastomas that is characteristically CD34-deficient by immunohistochemistry. Six myofibroblastomas were studied by immunohistochemistry and fluorescence in situ hybridization (FISH) for RB1. Patients included five women and one man, aged 41-85 years (median, 52.5). Tumor size ranged from 0.4 to 1.5 cm (mean, 0.95). Tumors showed spindle cell morphology in five cases and epithelioid features in one case. Two tumors showed complete lack of CD34 staining. The remaining showed weak focal or weak patchy CD34 staining. Dichotomous staining was seen in one case with CD34-positive spindle cell areas and CD34-negative myxoid areas. All six tumors showed ER expression, five of six showed desmin expression, and four of six showed bcl-2 positivity. Two of six (33.3%) tumors showed deletion of RB1 by FISH, including one that showed loss of Rb immunohistochemical staining. Myofibroblastomas uncommonly show absent/focal expression of CD34, a potential diagnostic pitfall, particularly in small samples. Characteristic staining with other immunohistochemical markers is seen which can aid in confirming the diagnosis. These tumors may harbor deletion of RB1, similar to CD34-positive myofibroblastomas, and this deletion may not correlate with loss of Rb by immunohistochemistry.

Atypical Spindle Cell Lesion of Larynx: A Rare Benign Condition mimicking Malignancy

ABSTRACT Atypical spindle cell lesion of larynx is a very rare condition usually misdiagnosed as malignant spindle cell tumor, requiring immunohistochemical (IHC) studies for reaching a correct diagnosis. We present a case of a 75-year-old male patient, who presented to the ear, nose, and throat casualty in stridor, and was tracheostomized. Videolaryngoscopy revealed a huge irregular growth filling the supraglottis. Biopsy of the growth suggested a reactive fibroblastic proliferation with atypia. The patient was again subjected to biopsy and it revealed well-differentiated squamous cell carcinoma (SCC). Total laryngectomy was done. The specimen on histopathological examination revealed atypical spindle cell lesion, and on IHC revealed a benign inflammatory spindle cell neoplasm. Here, we discuss the difficulty in making a decision on definitive treatment for such a condition and the importance of histopathological diagnosis of this condition for better understanding of its management. How to cite this article Dandala SR, Panuganti A, Kumuda P. Atypical Spindle Cell Lesion of Larynx: A Rare Benign Condition mimicking Malignancy. Int J Phonosurg Laryngol 2017;7(1):31-35.

Characterization of the leiomyomatous variant of myofibroblastoma: a rare subset distinct from other smooth muscle tumors of the breast

Mammary myofibroblastoma is a benign spindle cell tumor that can show variable morphologic patterns and lines of differentiation. Myofibroblastoma belongs to a family of CD34-positive tumors with similar morphology that show a deletion of 13q14, which includes RB1 and FOXO1A genes. A subset of these tumors demonstrates distinct smooth muscle differentiation. We aimed to characterize 4 cases of the leiomyomatous variant of myofibroblastoma arising in the breast by clinicopathological, immunohistochemical, and molecular means. All 4 examples arose in women aged 41 to 62 years (median, 46.5 years). Tumors ranged in size from 1.7 to 2.5 cm (median, 2.2 cm). Morphologically, all tumors were characterized by bundles of smooth muscle cells with elongated cigar-shaped nuclei and eosinophilic cytoplasm. All 4 tumors showed diffuse positive staining with desmin, caldesmon, smooth muscle actin, estrogen receptor, and Bcl-2. CD34 staining was diffusely positive in 2 cases, was weak and patchy in 1 case, and was negative in 1 case. Two (50%) of 4 tumors showed deletion of RB1 by fluorescence in situ hybridization. Loss of Rb staining was seen in 1 tumor with RB1 deletion by fluorescence in situ hybridization, whereas intact Rb staining was observed in 1 nondeleted case studied. In conclusion, this rare variant of myofibroblastoma is a distinct subgroup of tumors among an already uncommon category of (smooth muscle) breast tumors. Some reported examples of "parenchymal leiomyoma" may represent the leiomyomatous variant of myofibroblastoma.

Radiologic and Histologic Presentation of Male Mammary Myofibroblastoma

Mammary myofibroblastoma is a rare mesenchymal neoplasm that typically presents in older men and women. Less commonly, these benign tumors may also occur in soft tissues located outside of the breast, in which case they are referred to as mammary-type myofibroblastomas. The histologic composition of this benign spindle cell tumor can be markedly varied. We present a case of a large mammary myofibroblastoma in a male patient and discuss the typical imaging and histologic makeup of these tumors.

Mammary-Type Myofibroblastoma: A Report of Two Cases.

Mammary-type myofibroblastoma (MFB) is a rare, benign spindle cell neoplasm occurring along the milkline, with extension from the mid-axilla to the medial groin. It is histologically and immunohistochemically identical to MFB of the breast and is part of a spectrum of lesions that includes spindle cell lipoma and cellular angiofibroma. Recently, we experienced two cases of mammary-type MFB involving male patients aged 30 and 58 years, respectively. The tumors were located in the right scrotal sac and in the right axilla. Wide excisions were performed. Microscopically, the masses were composed of haphazardly arranged, variably sized fascicles of bland spindle cells and were admixed with mature fat tissue. The spindle cells in both cases showed immunopositivity for desmin and CD34 and negativity for smooth muscle actin. Loss of retinoblastoma (RB)/13q14 loci is a characteristic genetic alteration of mammary-type MFB, and we identified loss of RB protein expression by immunohistochemical staining. We emphasize the importance of awareness of this rare neoplasm when a spindle cell neoplasm is accompanied by desmin immunopositivity. The second patient was alive without recurrence for 20 months, and the first patient had not been followed.