Infantile myofibromatosis: Excellent prognosis but also rare fatal progressive disease. Treatment results of five Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry

Late Relapse in Genetically Determined Infantile Myofibromatosis. A Case Report and Brief Focus on Recurrences

BACKGROUND

Infantile myofibromatosis (IM) is a rare disorder characterized by benign tumors in the skin, subcutaneous tissue, muscle, and occasionally viscera. IM can be hereditary due to PDGFRB or NOTCH3 variants. Treatment is mainly conservative or surgical. Combination regimens have been used in case of disseminated disease.

OBSERVATION

We present relapsed disease of IM 11 years after diagnosis in a 2-year-old child initially treated by microscopically complete resection. A new heterozygous c.1687G>A (p.Glu563Lys) mutation in the PDGFRB gene was identified (considered likely pathogenic).

CONCLUSIONS

In association with initial treatment, genetic testing is crucial for tailored clinical practice and follow-up in patients diagnosed with IM.

Pneumothorax revealing late recurrence of infantile myofibromatosis

Adult recurrence of infantile myofibromatosis is exceptional. Here, we report the case of a 23-year-old woman with a late recurrence of infantile myofibromatosis revealed by spontaneous pneumothorax. The chest computed tomography scan found both cavitary and nodular bilateral pulmonary lesions. In infancy, she had multicentric myofibromatosis with digestive, cutaneous, and bone involvement, spontaneously regressive before the age of 15 months. Histological analysis of lung samples showed identical findings as from the cutaneous biopsy performed in infancy, confirming the recurrence of infantile myofibromatosis as pulmonary metastasis. New biopsy and long-term follow-up are highly recommended in the management of such cases.

Generalized Infantile Myofibromatosis with Extensive Small Bowel Involvement in a Neonate

Infantile myofibromatosis is a rare benign congenital tumour that often regresses spontaneously but may pose therapeutic challenges in its widespread visceral form. We present the case of a full-term neonate with generalized infantile myofibromatosis including ubiquitous subcutaneous and muscular nodules, a tumour in the mastoid and disseminated intestinal involvement. The intestinal tumours led to a mechanical ileus with intestinal perforation within the first days of life. After partial small bowel resection and necessary proximal jejunostomy the boy was dependent on total parenteral nutrition. Chemotherapy with vinblastine and methotrexate was started and was temporarily supplemented with imatinib. Feeding stayed impossible despite tumour shrinkage. At the age of 4.5 months, restoration of intestinal continuity with further stricturoplasties was performed which - for the first time - allowed complete oral feeding. Chemotherapy was continued for further two months. Currently, the child is in good general condition with growth and further disease regression. This report suggests that massive visceral involvement of infantile myofibromatosis may require extensive intestinal surgery, as conservative therapy cannot resolve the disease and its sequelae.

Congenital Infantile Myofibroma: The Importance of Molecular Diagnosis

Infantile myofibromatosis is an uncommon soft tissue neoplasm that may present at birth or in early infancy. Although rare, this neoplasm is one of the most common benign fibrous tumors of infancy. Even though these tumors do not spread, they can compress or damage nearby organs. There is not an established management protocol, but it is advisable to maintain periodic clinical and imagological control until stability. Watchful waiting is an option to consider in the absence of problematic symptoms and visceral involvement. We report a case of solitary infantile myofibromatosis, without visceral involvement. It showed an initial rapid growth, raising concern among medical doctors and motivating soft tissue biopsy, always recommended as the clinical picture deviates from the classic presentation. Histology interpretation is often challenging, making genetics and clinical evaluation essential to exclude and prevent the misdiagnosing of more aggressive lesions.

Myofibroma mimicking peripheral nerve sheath tumour with ulnar nerve compression symptoms

We report a case of myofibroma encasing the ulnar nerve on the medial aspect of the left arm with motor and sensory deficit secondary to compression. Initially, the tumour appeared to be a benign peripheral nerve sheath tumour based on preoperative imaging, with clinical examination positive for left hand clawing and a positive Wartenberg's and Froment's sign. However, intraoperative dissection demonstrated that the mass did not originate from the ulnar nerve proper, lowering suspicion for a peripheral nerve sheath tumour. Histopathological analysis showed spindle cell neoplasm, consistent with myofibroma. The patient underwent hand occupational therapy subsequently, with improvement of grip strength from 5 lb to 12 lb by 4 months postoperatively and resolution of clawing of the hand postoperatively. We discuss differentiating features for this rare occurrence of solitary adult myofibroma, where the final diagnosis was only made after formal histopathological analysis.