A case report of desmoplastic fibroblastoma in a 2-year-old child

Abstract

Desmoplastic fibroblastoma is a benign tumor. It was first reported by Evans in 1995 and is also known as collagenous fibroma. We encountered a case of desmoplastic fibroblastoma in clinical practice, wherein a 2-year-old girl presented with the following specimen from the scalp—a piece of gray–white nonplastic tissue with a volume of 2 × 1.5 × 1 cm. The cut surface was gray–white, solid, and of moderate consistency. Microscopically, there were only a few tumor cells, composed of spindle-shaped and stellate fibroblasts embedded in a dense collagenous or myxoid matrix, with minimal cellular atypia. The patient underwent surgical procedures for resection and is recovering well. This report provides an opportunity for experts and scholars to learn and communicate together. A new breakthrough has been achieved with regard to the age range of onset for this disease.

Introduction

Desmoplastic fibroblastoma (DFB) is a benign tumor composed of abundant collagen and a few scattered spindle-shaped or star-shaped fibroblasts. It was first reported by Evans in 1995 and is also known as collagenous fibroma.^1,2 It mainly occurs in the age group of 40–60 years and affects more males than females. ³ The patient presented in this case, a 2-year-old toddler, has expanded the age range for the onset of this disease. DFB is often characterized by local slow-growing painless masses, which are most commonly detected in the upper arms, shoulders, back, and forearms, followed by the lower limbs, feet, hands, and head and neck, usually subcutaneously or intramuscularly. Imaging manifestations include computed tomography showing that the mass has a clear perimeter, uneven density, mainly low-density changes, and a few isodense areas, with no enhancement on contrast-enhanced scans. Magnetic resonance imaging shows that the signal of the mass is not uniform, being mainly isointense, and that the perimeter is clear. Most of the treatment methods include local complete excision, and the postoperative prognosis is usually curable, with no recurrence or metastasis.

Case presentation

A 2-year-old girl (admitted to the General Hospital of the Northern Theater Command, No.83, Wenhua Road, Shenhe District, Shenyang, for treatment in May 2019) visited the clinic after a mass was accidentally discovered under the scalp. The general appearance of the mass was as follows: (scalp) one piece of off-white nonplastic tissue, with a volume of 2 × 1.5 × 1 cm, off-white cut surface, solid, medium in quality. Its microscopic appearance was as follows: the tumor cells were sparse and consisted of spindle-shaped and stellate-shaped fibroblasts embedded in a dense collagenous or mucoid matrix as well as myofibroblasts. The cell heterogeneity was not significant. The blood vessels in the interstitium were not obvious, and focal mucinous degeneration was occasionally observed (Figures 1 and 2). Immunohistochemical analysis showed positivity for CD34, Vim, and FOSL1, and the results were negative for CK, SMA, Desmin, CD99, S100, β-catenin, CD10, Ki67 < 1%+ (Figures 3 and 4).

Figure 1.

Hematoxylin and eosin staining showing the tumor cells.

Figure 2.

Hematoxylin and eosin staining showing the tumor cells.

Figure 3.

Positive immunohistochemical staining for CD34 and Vim.

Figure 4.

Positive immunohistochemical staining for FOSL1.

Discussion

DFB generally presents as a nodular or subcircular mass with a clear perimeter; no capsule or partly covered by a pseudocapsule, with an average diameter of 4.5 cm (range: 1.0–20 cm); white or off-white cut surface; and tough or elastic texture. The histological form is usually a tumor substance composed mainly of sparse spindle-shaped or stellate fibroblasts and a large number of dense collagen fibers, and the collagen fibers are arranged in disorder and not in bundles. The nuclear chromatin is homogeneous, fine or vacuolated; small nucleoli can be seen; and mitotic figures are rare. The local interstitium may be fibrous or exhibit myxoid changes; moreover, it may contain a small amount of thin-walled small blood vessels. The results of immunohistochemistry were as follows: tumor cells expressed vimentin, focally or weakly positively expressed actins, and specific nuclei expressed FOSL1. In addition, DFB involves cytogenetic abnormality in the chromosome region 11q12. Macchia et al. ⁴ found that the 11q12 rearrangement in this tumor involves the FOSL1 gene, which is known to be activated in lung, bowel, breast, prostate, and head and neck tumors but has not been detected in other soft tissue tumors. For rearrangement, detection of FOSL1 gene rearrangement via fluorescence in situ hybridization (FISH) or detection of FOSL1 protein via immunohistochemistry are helpful for diagnosis. Our results are almost consistent with those of tests conducted by other research groups (e.g. Desmin (−),^5–7 S100 (−),^5,6,8 SMA (−), ⁶ β-catenin (−), ⁷ and CK (−)). ⁸

Regarding its differential diagnosis, the following six diseases need to be identified. 1. Invasive fibromatosis: the tumor cells express β-catenin, and molecular testing shows a mutation in the β-catenin gene. 2. Nuchal fibroma: the disease mainly occurs on the back of the nape, between the shoulders, and around the spine. The periphery of the lesion is unclear. It is mainly composed of thick collagen bundles and few and scattered fibroblasts. Proliferative tumors can be seen around the lesion, with small nerve bundles. 3. Tenosynovial fibroma: the disease mostly occurs in the distal limbs, especially the hands, fingers, and wrists, often connected to tendons or tendon sheaths. Under the microscope, the lesions are mostly lobules, mainly composed of collagen fibers, scattered spindle-shaped fibroblasts, and slit-like vascular spaces. Tumor cells do not express FOSL1. 4. Nodular fasciitis: the disease does not involve any capsule, can extend into the surrounding fat or muscle tissue, and is composed of proliferating myofibroblastic cells. Moreover, mitotic figures can be seen, along with interstitial myxedema-like, common erythrocyte extravasation, and the cells diffusely express SMA and CD10. 5. Neurofibroma: the tumor cells are short, spindle-shaped, or oval; can be arranged in waves; and diffusely express S100 and SOX10. 6. Low-grade malignant fibromyxoid sarcomas: multifibrous and myxoid areas are distributed alternately, the density of tumor cells is relatively high, often arranged in a spiral shape, tumor cells express MUC4, and FISH detection can show CREB312 gene translocation.

DFB is a rare tumor that primarily occurs in adults, with an average diagnosis age of approximately 50 years. ⁹ However, according to current research, there exists a significantly wide age range among patients with DFB, with the youngest case being a 5-year-old boy and the oldest an 83-year-old woman.^10,11 Notably, to date, only one case involving a child has been recorded in the medical literature. A detailed report describing this specific case involves the onset of symptoms in a 2-year-old child, providing another instance of pediatric presentation and significantly broadening and updating the previously established age range for the disease, which may be 2 to 83 years. This finding provides an important reference point for most pathologists and offers a valuable theoretical basis for medical professionals to make accurate diagnoses in similar cases. It should be noted that although DFB is a benign tumor, it exhibits local invasiveness, ¹² and extensive resection is the preferred therapeutic approach. ⁶ Additionally, for pregnant patients with DFB, active monitoring combined with timely surgical intervention is an effective management strategy. ⁵

The value of this case report lies in three breakthroughs:

Breaking through the cognitive boundaries of the disease (core value) and redefining the age spectrum of onset. Current medical consensus classifies this disease within the age group of 40–60 years (World Health Organization (WHO) classification standards). The diagnosis of this 2-year-old child proves that this tumor can occur in infancy (two years earlier than the lowest age recorded in the literature), suggesting that diagnostic criteria need to include the differential category of “rare tumors in children,” revealing the mechanisms of clinical heterogeneity. The differences in presentation between child and adult cases suggest the possible existence of embryonic tumor subtypes (requiring molecular identification verification) and different driving gene expression patterns compared with adults.

Correcting clinical practice guidelines (clinical value) and optimizing early diagnosis pathways, establishing a diagnostic tree for pediatric soft tissue tumors, and increasing the differential entries for this disease (especially distinguishing it from infantile fibrosarcoma). Regarding the basis for adjusting treatment strategies, the scope of surgical resection should consider the developmental characteristics of children’s organs (as opposed to extensive resection in adults). The potential for special treatment responses in children should be considered, as adult patients often undergo radiotherapy; however, infants are more sensitive to radiation, necessitating avoidance of radiotherapy’s impact on developing tissues.

Promoting the translation of fundamental research (scientific value), providing key research models, and offering clinical samples for establishing “age-related tumor evolution” animal models. Considering the young age of onset in the child, the mechanisms may involve differences in gene mutation expression, embryonic developmental remnants, and other special mechanisms, which provide direction for subsequent fundamental research.

Of course, this case also has some limitations. For example, the follow-up of the patient was not conducted appropriately, and there is a lack of imaging data. However, this does not affect the reason for reporting this case—the unique age of onset.

In conclusion, although DFB is extremely rare or rare in childhood, it is an objective and real situation. In future clinical work, if similar children with soft tissue masses are encountered, both clinicians and pathologists should consider including the disease as one of the possible diagnoses or differential diagnoses to avoid inappropriate diagnosis. Misdiagnosis can lead to clinical undertreatment or overtreatment. The reporting of this study conforms to the Case Report (CARE) guidelines. ¹³

Supplemental Material

sj-pdf-1-imr-10.1177_03000605251379965 - Supplemental material for A case report of desmoplastic fibroblastoma in a 2-year-old child

Supplemental material, sj-pdf-1-imr-10.1177_03000605251379965 for A case report of desmoplastic fibroblastoma in a 2-year-old child by Yihao Tian and Jian Ming in Journal of International Medical Research