Giant juvenile fibroadenoma: A case report.

INTRODUCTION AND IMPORTANCE: Breast pathology in adolescents is rare and predominantly benign, with abnormalities including congenital anomalies, infections, mastodynia, nipple discharge, and mostly benign breast masses. Fibroepithelial tumors, the most common type, form a heterogeneous group that includes benign, borderline, and malignant entities such as phyllodes tumors. Differentiation of these tumors, especially various types of fibroadenomas, requires histopathological examination due to their similar radiological appearances and lesion heterogeneity. Recognizing the nature of these lesions is crucial to avoid missing malignant forms with metastatic potential. Giant juvenile fibroadenoma is a quite rare benign fibroepithelial tumour, that cannot be differentiate from phyllodes tumors before anatomopathological examination. CASE REPORT: We report the case of a 14-year-old patient who presented with a rapidly enlarging mass in the left breast, and the diagnosis of giant juvenile adenofibroma was confirmed after surgical treatment. CLINICAL DISCUSSION: Giant juvenile fibroadenomas occurs in adolescent girl and constitutes 0.5 % - 4 % of all fibroadenomas cases. When it exceeds 5 cm, weighs more than 500 g, or occupies more than 4/5 of the breast, it is considered as giant. It is characterized by a rapid increase in size, causing distortion and compression of the breast. Breast ultrasound is the first imaging modality, showing a large, well-limited hypo or iso echoic mass. The main differential diagnosis should be made with phyllodes tumors. The diagnosis is considered based on clinical and radiological features but is confirmed only after surgical excision of the mass and histological study. CONCLUSION: The discovery of a breast mass in an adolescent should prompt further investigations to avoid overlooking a fibroepithelial tumour. The most probable diagnoses are giant juvenile fibroadenoma and phyllodes tumors.

Fibroepithelial Neoplasm with Hybrid Features of Benign Phyllodes Tumor, Juvenile Papillomatosis, and Juvenile Fibroadenoma: A Case Report.

Phyllodes tumor is an uncommon breast fibroepithelial neoplasm mainly found in middle-aged patients, presenting a morphologic continuum from benign to malignant. Juvenile papillomatosis represents a rare benign proliferative breast tumor primarily affecting young individuals and carries a potential elevated risk of subsequent breast cancer development. Juvenile fibroadenoma is a well-circumscribed biphasic neoplasm that often occurs in adolescent girls, characterized by a pericanalicular growth pattern with usual-type epithelial hyperplasia and gynaecomastia-like micropapillary proliferation. Herein, we present an unusual example of a 26-year-old woman with a left breast outer lower quadrant palpable mass. Ultrasonography identified a 5.9 cm lobulated hypoechoic solid mass with scattered small cysts. The preoperative biopsy initially diagnosed a fibroepithelial lesion, considering giant cellular fibroadenoma and phyllodes tumor in the differential. Subsequent complete excision revealed areas of benign phyllodes tumor features closely admixed with distinctive elements such as prominent multiple cysts exhibiting apocrine and papillary apocrine metaplasia, duct papillomatosis, and duct stasis characteristic of juvenile papillomatosis, and hyperplastic ductal epithelium with micropapillary projections demonstrating a pericanalicular growth pattern indicative of juvenile fibroadenoma. The diagnosis was conclusively established as a fibroepithelial lesion with combined features of benign phyllodes tumor, juvenile papillomatosis, and juvenile fibroadenoma. Further investigation uncovered a family history of breast cancer. Molecular analysis revealed a pattern of unique and overlapping mutations within these distinct histopathological areas. This unusual presentation with hybrid features within a single tumor is described for the first time in the literature along with the molecular signature of the individual components.

Giant juvenile fibroadenomas with and without prominent pseudoangiomatous stromal hyperplasia (PASH)-like change: clinicopathological and molecular characteristics.

AIMS: Juvenile fibroadenomas (JFA) are biphasic fibroepithelial lesions (FEL) usually occurring in adolescent female patients. Giant (G) JFA, like other FEL, may exhibit prominent pseudoangiomatous stromal hyperplasia (PASH)-like change. We sought to determine clinicopathological and molecular characteristics of GJFA with and without PASH. METHODS AND RESULTS: Archives were searched for cases of GJFA (1985-2020). All were stained for androgen receptor (AR), beta-catenin, CD34 and progesterone receptor (PR). Cases were sequenced using a custom 16-gene panel - MED12 (exons 1 and 2), TERT promoter (-124C>T and -146Ctable>T), SETD2, KMT2D, RARA (exons 5-9), FLNA, NF1, PIK3CA (exons 10, 11 and 21), EGFR, RB1, BCOR, TP53, PTEN, ERBB4, IGF1R and MAP3K1. Twenty-seven GJFA from 21 female patients aged 10.1-25.2 years were identified. Size ranged from 5.2 to 21 cm. Two patients had multiple, bilateral and later recurrent GJFA. Thirteen (48%) cases showed prominent PASH-like stroma. All were positive for stromal CD34, negative for AR and beta-catenin and one case showed focal PR expression. Sequencing showed MAP3K1 and SETD2 mutations in 17 samples, with KMT2D, TP53 and BCOR aberrations in 10 (45%), 10 (45%) and seven (32%) cases, respectively. Tumours with a PASH-like pattern had higher prevalence of SETD2 (P = 0.004) and TP53 (P = 0.029) mutations, while those without PASH had more RB1 mutations (P = 0.043). MED12 mutation was identified in one case. TERT promoter mutation was observed in four (18%), including two recurrences. CONCLUSIONS: Gene mutations along more advanced phases of the proposed FEL pathogenetic pathway in GJFA are unusual, and suggest a mechanism for more aggressive growth in these tumours.

Giant Juvenile Fibroadenoma: Case Report and Review of the Literature.

Fibroadenomas are common benign breast tumors. Fibroadenomas that exceed 5 cm in diameter, weigh more than 500 g, or replace more than four-fifths of the breast are characterized as giant. A fibroadenoma diagnosed in patients during childhood or adolescence is characterized as juvenile. An extensive PubMed search of the literature in English up until August 2022 was performed. In addition, a rare case of a gigantic fibroadenoma in an 11-year-old premenarchal girl who was referred to our adolescent gynecology center is presented here. Eighty-seven cases of giant juvenile fibroadenomas have been reported in the literature along with our case. Patients with giant juvenile fibroadenoma presented at a mean age of 13.92 years and usually after menarche. Juvenile fibroadenomas are usually unilateral, occurring either in the right or the left breast; the majority of them are diagnosed when they are already more than 10 cm in size, and they are most frequently treated with total lump excision. Differential diagnosis includes phyllodes tumors and pseudo-angiomatous stromal hyperplasia. Conservative management is feasible, but surgical excision is recommended to patients with suspicious imaging features or when the mass grows rapidly.

Giant juvenile fibroadenoma in a 14-year old Chinese female: A case report.

BACKGROUND: A giant juvenile fibroadenoma (GJF) is a rare, benign breast tumor that affects females < 18 years of age. GJFs are generally suspected based on a palpable mass. GJFs influence breast shape and mammary gland development via the pressure effect from their enormous size. CASE SUMMARY: Herein we report a case involving a 14-year-old Chinese female with a GJF in the left breast. GJF is a rare, benign breast tumor that usually occurs between 9 and 18 years of age and accounts for 0.5%-4.0% of all fibroadenomas. In severe cases, breast deformation may occur. This disease is rarely reported in Chinese people and has a high clinical misdiagnosis rate due to the absence of specific imaging features. On July 25, 2022, a patient with a GJF was admitted to the First Affiliated Hospital of Dali University. The preoperative clinical examination and conventional ultrasound diagnosis needed further clarification. The mass was shown to be an atypical lobulated mass during the operation and confirmed to be a GJF based on pathologic examination. CONCLUSION: GJF is also a rare, benign breast tumor in Chinese women. Evaluation of such masses consists of a physical examination, radiography, ultrasonography, computer tomography, and magnetic resonance imaging. GJFs are confirmed by histopathologic examination. Mastectomy is not selected when the patient benefits from a complete resection of the mass with breast reconstruction and an uneventful recovery.

Fibroadenoma gigante juvenil y cirugía de reconstrucción: reporte de un caso y revisión de la bibliografía / Giant juvenile fibroadenoma and reconstruction surgery: A case report and literature review

El fibroadenoma es la lesión mamaria benigna más frecuente en la mujer joven, siendo el fibroadenoma gigante juvenil una entidad que aparece principalmente en menores de 25 años. Con una etiología actualmente no bien establecida, se caracteriza por ser una lesión tipo masa mayor de 5cm que puede ocupar más del 80% de la mama y que presenta un importante crecimiento con las consecuencias físicas y psicológicas que ello conlleva. A pesar de ser una lesión benigna, su evolución progresiva con un rápido crecimiento obliga a descartar malignidad, lo cual ocurre en menos del 0,2% de los casos. El diagnóstico se basa en una correcta anamnesis, exploración física y pruebas complementarias, siendo preferible la ecografía. El estudio anatomopatológico mediante biopsia permite confirmar el diagnóstico clínico de benignidad o descartar malignidad ante una evolución sospechosa. El tratamiento es quirúrgico y consiste en la escisión completa de la lesión variando la técnica quirúrgica realizada (desde cirugía conservadora hasta mastectomía con reconstrucción) según el tamaño de la lesión, las características de la mama y la edad de la paciente. (AU)

Fibroadenoma is the most common benign breast lesion in young women, being the giant juvenile fibroadenoma an entity that appears mainly in those under 25 years. With an etiology currently not well established, it is described as a mass type lesion greater than 5cm or that occupies more than 80% of the breast and presents significant growth, with the physical and psychological consequences that this entails. Despite being a benign lesion, its fast evolution and growth makes it necessary to rule out malignancy, which occurs in less than 0.2% of the cases. The diagnosis is based on a correct anamnesis, physical examination and complementary tests, preferable with ultrasound. The anatomopathological study by biopsy allows to confirm the clinical diagnosis of benignity or to rule out malignancy in the event of a suspicious evolution. Its management is surgical and consists of complete excision of the lesion, varying the surgical technique performed (from conservative surgery to mastectomy with reconstruction) according to the size of the lesion, the characteristics of the breast, and the age of the patient. (AU)

Abordaje quirúrgico inframamario en una paciente con un fibroadenoma gigante juvenil. A propósito de un caso y revisión de la bibliografía / Inframammary removal of giant juvenile fibroadenoma in an adolescent. Case report and review of the literature

Los tumores benignos más comunes de la mama son los fibroadenomas simples. Son tumores sólidos con tejido glandular y fibroso. Aquellos que presentan un tamaño mayor de 5cm se denominan fibroadenomas gigantes. Estos pueden presentar un rápido crecimiento, por lo que se debe realizar un diagnóstico diferencial con el tumor phyllodes u otras enfermedades mamarias.Presentamos el caso de una paciente de 15 años con un fibroadenoma que comenzó con asimetría mamaria y precisó tratamiento quirúrgico mediante abordaje inframamario y enucleación de la masa, con buen resultado estético posterior. Revisamos la bibliografía al respecto.(AU)

Simple fibroadenomas are the most frequent benign tumours of the breast. They are solid tumours with glandular and fibrous tissue. They can present as a mass greater than 5cm, called giant fibroadenomas. The presentation of a rapidly growing mass cannot be easily distinguished from phyllodes tumour or other pathologies.We report the case of juvenile fibroadenoma of the breast in a 15-year-old woman who presented at our hospital with breast asymmetry. She underwent fibroadenoma excision, using inframammary access with good cosmetic outcomes. A detailed literature search and management of these lesions are discussed.(AU)

Breast reconstruction using a tissue expander after enucleation of a giant fibroadenoma: A case report.

INTRODUCTION: Fibroadenomas are among the most common benign tumors in women. Juvenile giant fibroadenomas account for nearly 0.5% of all fibroadenomas. Due to its size, a giant juvenile fibroadenoma leaves a large defect or deformity after its resection. The optimal surgical management strategy for giant juvenile fibroadenomas remains unclear. Here, we report a case of successful breast reconstruction without residual deformity through gradual deflation of a saline-filled tissue expander after resection of a giant juvenile fibroadenoma. PRESENTATION OF CASE: A 14-year-old girl with a growing tumor in her left breast presented to a private clinic. Given that the tumor was 8 cm in size, phyllodes could not be ruled out. Consequently, she was referred to our hospital for further examination and treatment. Core needle biopsy confirmed the tumor to be a fibroadenoma. We resected the tumor and inserted a tissue expander filled with 120 mL of saline, matching the area of the large defect caused by tumor resection. We removed approximately 25 mL of saline every 3 weeks to aid normal mammary tissue enlargement. After completely draining saline from the tissue expander and confirming an acceptable enlargement of the residual mammary gland, we performed an operation to remove the tissue expander. Follow-up revealed that the symmetry and contour of the breast were excellent after the second operation. CONCLUSIONS: Our observations suggest that using a tissue expander to enlarge normal mammary tissue may help reconstruct large defects caused by excision of benign tumors.

Case report: Transformation of juvenile fibroadenoma to borderline phyllodes tumor in young lady.

INTRODUCTION: Fibroadenoma is the most common benign tumor found in young women. Transformation for Fibroadenoma to borderline phyllodes tumor is rare. Phyllodes tumor tends to recur locally due to the aggressive nature of the phyllodes tumor tissue, which tends to become malignant when recurrence occurs. PRESENTATION OF CASE: We report an 18-year-old woman with a lump in the right breast for one year, a mass in the upper lateral quadrant measuring 20x15x10cm; the lump felt mobile, supple, cystic. 2 years earlier, lumpectomy surgery with anatomical pathology of fibroadenoma mammae with 6 cm. A biopsy was performed, the result was a borderline phyllodes tumor. Neoadjuvant chemotherapy was performed with tumor reduction >50%, followed by wide excision surgery with tumor-free margins. The first one-year evaluation showed no signs of recurrence, and no signs of distant metastases were found. CONCLUSION: Our patient had a juvenile relapse FA which progressively changed to borderline tumor phyllodes borderline. We report this case to the need for continuous follow-up for fibroadenoma cases and the possibility of recurrence and becoming malignant.

Giant Juvenile Fibroadenoma of the breast in a 13-year-old Pakistani girl with excellent cosmetic outcome after subareolar enucleation - A case report.

INTRODUCTION: Fibroadenoma is the most common benign lesion of breast in young women, characterized by an aberrant proliferation of both epithelial and mesenchymal elements. It is termed giant fibroadenoma when it is larger than 5 cm or weighs more than 500 g with an incidence of 0.5-2% of all fibroadenomas. PRESENTATION OF CASE: In this report, we discuss a case of a 13-year-old Pakistani girl who presented with a giant juvenile fibroadenoma in left breast and was treated by a subareolar lump excision through a periareolar incision with excellent cosmetic outcome. To the best of our literature search, this is the first case of giant juvenile fibroadenoma in an adolescent being reported from Pakistan. DISCUSSION: Surgical management of giant juvenile fibroadenoma in immature breast is challenging as it may either result in asymmetric defect or damage to developing breast tissue resulting in long term poor outcomes. Surgical decision should be carefully undertaken and reported for future reference in such cases. CONCLUSION: The diagnosis and management of giant juvenile fibroadenoma can be challenging because these tumors clinically and histologically mimic phyllodes tumor due to their rapid growth and large size. Excision through a periareolar approach for fibroadenomas located in subareolar region provides good cosmetic results in these patients with minimal scar visibility.

A Diagnostic Enigma - A Rare Presentation Of Juvenile Fibroadenoma In A Premenarchal Girl.

AIM: Reporting a rare case of a teenage girl, with a bizarre clinical presentation of a benign breast condition, that too is uncommon at her age. CASE: A 14-year-old pre-menarche girl presented with a rapidly progressing lump that involved the entire breast within 3 months. It was associated with ulceration of the overlying skin along with destruction of the nipple-areola complex. RESULTS: During the pre- operative workup, a neoplastic etiology was suspected, but post- operative histopathology revealed it to be giant juvenile fibroadenoma. CONCLUSION: This case emphasizes on the benign character of breast masses in the adolescent age group. Despite the massive volume and appearance, the opportunity of a conservative surgical approach should be sought.

Giant juvenile fibroadenoma in an adolescent female: A case report.

Giant juvenile fibroadenoma in adolescents should be dealt with utmost caution as this may be associated with anxiety, fear, and emotional factors. The treatment should aim for preserving the normal contour of the breast along with appealing scar.

Juvenile Fibroadenoma in a Four-Month-Old Male Infant.

Teaching point: As juvenile fibroadenoma is radiologically indistinguishable from a (malignant) phyllodes tumor, a core biopsy is decisive for both treatment and follow-up.

Giant fibroma of breast in an adolescent female by inverted "T" incision: A case report and literature review. / é’æ˜¥æœŸä¹³è ºå·¨å¤§çº¤ç»´è ºç˜¤è¡Œå€’"T"型切口1ä¾‹å¹¶æ–‡çŒ®å¤ä¹ .

Giant fibroma of the breast in adolescence is a benign tumor of the breast that occurs in a special period in women, often in adolescent women aged 18-25 years old. These tumors are characterized by short course and large size. They are rare in clinic and easy to be misdiagnosed. We report a case of 22 cm-pubertal breast giant fibroadenoma which underwent inverted "T" incision resection. The diagnosis, pathological characteristics, and treatment of adolescent giant fibroadenoma of the breast are also discussed based on literature.

Surgical management of giant juvenile fibroadenoma with skin reducing tumor resection and immediate breast reconstruction: A single-center experience.

BACKGROUND AND OBJECTIVES: Giant juvenile fibroadenoma (GJF) is a rare benign tumor that disfiguring affects the breast shape and quality of life of patients. This study aimed to report the experience of GJF management. METHODS: A Wise-pattern skin reducing tumor resection followed by immediate breast reconstruction with a dermal flap pocket was used. The long-term outcomes were assessed retrospectively by BREAST-Q questionnaire from 2008 to 2018. RESULTS: The study included eight patients with GJF. All patients achieved satisfactory results without severe complications. The BREAST-Q revealed that postoperative scores for satisfaction with breasts (69.3 ± 17.6) and sexual wellbeing (62.3 ± 27.6) were higher than the normative scores. The psychosocial wellbeing (69.7 ± 14.6) and physical wellbeing-chest (86.8 ± 13.0) scores were slightly lower than the normative scores. CONCLUSION: Although GJF is a benign tumor, it should be surgically removed. And the Wise-pattern skin reducing tumor resection with immediate breast reconstruction is a proper way to improve patients' satisfaction with breast size and shape and quality of life.

Malignant transformation of phyllodes tumor: a case report and review of literature.

Malignant phyllodes may transform from benign phyllodes; low-aggressive malignant phyllodes tumor is manageable by locally wide excision.

Fibroadenoma gigante juvenil: reporte de un caso / Giant juvenile fibroadenoma: Case report

Resumen ANTECEDENTES: El fibroadenoma gigante es raro; suele aparecer en mujeres entre 10 y 18 años. Se caracteriza por el crecimiento rápido de una tumoración encapsulada. De 0.5 a 4% corresponden a una forma especial descrita como fibroadenoma gigante o juvenil. La ecografía es el método de elección para el diagnóstico primario. Si bien la causa principal de una masa asimétrica mamaria en niñas es benigna, la extirpación quirúrgica temprana es la mejor manera de asegurar un buen resultado estético. CASO CLÍNICO: Paciente femenina de 12 años, llevada a la consulta debido al aumento de tamaño de la mama izquierda en el lapso de los tres meses previos. Sin antecedentes personales de importancia, sin cirugías previas, sin consumo de medicamentos y sin alergias conocidas. En la exploración física se apreció la asimetría de las mamas debido al aumento de tamaño de la izquierda; la forma de la areola y el pezón sin alteraciones. Se palpó una tumoración de bordes delimitados, consistencia homogénea blanda que ocupaba toda la glándula mamaria de aproximadamente 20 cm. CONCLUSIONES: El fibroadenoma juvenil es una lesión de crecimiento rápido y exponencial que distorsiona la asimetría y afecta la calidad de vida de la paciente. Es importante establecer el diagnóstico diferencial con tumoraciones mamarias para poder aclarar las dudas de nuestras pacientes acerca de su pronóstico. En pacientes jóvenes es importante tener en cuenta un solo acceso para la reconstrucción.

Abstract BACKGROUND: Giant fibroadenoma is rare; It usually appears in women between 10 and 18 years old. It is characterized by the rapid growth of an encapsulated tumor. From 0.5 to 4% correspond to a special form described as giant or juvenile fibroadenoma. Ultrasound is the method of choice for primary diagnosis. Although the main cause of an asymmetric mammary mass in girls is benign, early surgical removal is the best way to ensure a good aesthetic result. CLINICAL CASE: Female patient of 12 years, taken to the consultation due to the in-crease in size of the left breast in the span of the three previous months. No significant personal history, no previous surgeries, no medication and no known allergies. On physical examination, the asymmetry of the breasts was seen due to the increase in size of the left; the shape of the areola and nipple without alterations. A tumor of delimited edges was palpated, smooth homogenous consistency that occupied the entire mam-mary gland of approximately 20 cm. CONCLUSIONS: The juvenile fibroadenoma is a rapidly growing and exponential lesion that distorts the asymmetry and affects the quality of life of the patient. It is important to establish the difference diagnosis with mammary tumors in order to clarify the doubts of our patients about their prognosis. In young patients it is important to consider only one access for reconstruction.

A case report of juvenile giant fibroadenoma of the breast: How common?

Breast lesions are rare prepubescents. The majority of breast lesions in this age group are benign. The most common of these rare lesions is juvenile fibroadenoma, which accounts for only 0.5% of all fibroadenomas. It is uncommon to have a palpable lesion in juveniles as very small lesions show obvious asymmetry. Fibroadenomas can grow to a large size, and surgical intervention is cosmetically challenging, especially in achieving symmetry in a developing breast. A 12-year-old girl presented with right breast swelling associated with tenderness. The mass had initially been small on self-discovery 1 year previously and grew with time. There was no overlying skin changes or any significant risk factors for breast malignancy. Triple assessment showed features of fibroadenoma, but we were unable to rule out a phyllodes tumor. She subsequently underwent excision biopsy of the right breast lesion for symptomatic control and histopathology examination (HPE) of the lesion. The HPE report confirmed the diagnosis of fibroadenoma. The patient recovered well postoperatively with no complications. Juvenile breast lesions are rare, and it is a challenge to provide an adolescent with the best treatment in terms of clinical and psychological care. A surgical approach requires meticulous planning to ensure a fine balance between adequate resection and the best cosmetic outcome for a developing breast.

Giant juvenile fibroadenoma in a 9-year-old: A case presentation and review of the current literature.

Juvenile fibroadenoma is the most common breast mass in adolescents accounting for 0.5-4% of all cases of fibroadenomas. Giant fibroadenomas are well-circumscribed, firm breast masses characterized by proliferation of epithelial and connective tissue. They are defined as being larger than 5 cm or weighing more than 500 g. The peak age has been reported between the ages of 17 and 20, with less than 5% of these in patients less than 18-years-old.We present a 9-year-old, pre-menstrual, Nigerian female with no known family history of breast masses or cancers who developed spontaneous giant fibroadenoma measuring approximately 13  cm × 13 cm. Rapid growth of a breast mass can be of great concern to such young patients whose breasts are in the early formative stages. It is important to promptly rule out malignant processes or phyllodes tumor, and educate young patients and their families on treatment options that fit their unique concerns and circumstances.

Fibroepithelial Lesions in the Breast of Adolescent Females: A Clinicopathological Study of 54 Cases.

Fibroepithelial lesions (FELs) are the most frequent breast tumors in adolescent females. The pubertal hormonal surge could impact the growth and microscopic appearance of FELs in this age group. In this study, we evaluate the morphology and clinical behavior of FELs in adolescents. We searched the 1992-2012 pathology data base for FELs in females 18 years old or younger (F ≤18 years). Seven FELs from 1975 to 1983 were also included. Three pathologists reviewed all available material. Patient (pt) characteristics and follow-up information were obtained from electronic medical records. Forty-eight F ≤18 years had 54 FELs with available slides. Thirty (67%) pts were Caucasian, 12 (27%) African-American, two (4%) Hispanic, one (2%) Asian; three were of unknown race/ethnicity. Median age at diagnosis was 16 years. Median age at menarche was 12 years; most (96%) FELs occurred after menarche (median interval 48 months). All patients underwent lumpectomy; one required subsequent mastectomy. The FELs were 34 fibroadenomas (FAs) (11 usual, 23 juvenile), and 20 phyllodes tumors (PTs) (16 benign, one borderline and three malignant). Eight (35%) juvenile FAs showed slight intratumoral heterogeneity. The mean mitotic rate was 1.3 mitoses/10 high-power fields (HPFs) (range, 0-6) in usual FAs, 1.8/10 HPFs in juvenile FAs, 3.1/10 HPFs in benign PTs, 10/10 HPFs in the borderline PT and 17/10 HPFs in malignant PTs. The mean follow-up for 29 pts with 33 FELs was 44 months. Two (10%) PTs recurred locally (a benign PT at 18 months, and a borderline PT at 11 months). Both recurrent PTs had microscopic margins <1 mm. Mitotic activity in FAs from adolescents can be substantial and this finding should be interpreted cautiously. Awareness of the morphologic features of FELs in adolescents is important to avoid overdiagnosis of PTs, which can lead to additional unnecessary and potentially disfiguring surgery.