Infantile digital fibromatosis (inclusion body fibromatosis) observed in a baby without finger involvement.

A 9-day-old male baby was hospitalized after his birth due to some swells under the skin. The hard consistency nodules observed under the skin all over the body of the patient were of different size, and presented lesions, among which the biggest was 1 × 1 cm. No lesions were observed on the fingers. By superficial ultrasonography, multiple isoechoic hypoechoic lesions were observed among the muscle plan. In thoracolumbar magnetic resonance imaging, multiple massif lesions retaining peripheral contrast (the biggest was 1.7 × 1.4 cm large) had been observed under the skin muscle plans, between the muscles of the extremities. The biopsy was positive for smooth muscle actin, but negative for desmin, S100, and CD34. These findings were diagnosed as infantile digital fibromatosis (IDF) (inclusion body fibromatosis). The case was presented with an objective to illustrate and remind that IDF can be observed in babies without finger involvement.

What was known?

Inclusion body fibromatosis can be seen at birth.

Introduction

Infantile digital fibromatosis (IDF) is a smooth, firm, erythematous or skin-colored nodule on the dorsal or lateral surfaces of the distal phalanges of the fingers and toes. More than 80% of tumors are present in infancy.[1] These rare tumors are also known as fibrous tumors in babyhood, digital fibrous tumors in childhood, IDF, juvenile dermatofibroma, and digital fibrous tumor of childhood.[2-4]

In this report, an IDF has been diagnosed in a 9-day-old baby without finger involvement.

Case Report

A 9-day-old male baby was hospitalized after his birth due to some swells under the skin. There was no specific event in his prenatal history. According to the information obtained, the patient was born by spontaneous vaginal birth at home as the third child of a 26-year-old mother during her 38th week of pregnancy. According to the information gathered from the family, it was determined that the mother and the father of the patient were second-degree parents (their parents are cousins). In physical examination, the general condition of the patient was good, and he presented open awareness. His spontaneous movements were normal. His suction, searching, catching and moro reflexes were operational. The weight of the patient was 2950 gr, the height was 49 cm, and the head circumference was 34 cm. The frontal fontanel was 2 × 2 and at a normal cambering level. The hard consistency nodules observed under the skin all over the body of the patient were of different sizes, and presented lesions, among which the largest was 1 × 1 cm [Figure 1]. There were no lesions on the fingers.

Figure 1

Nodules observed under the skin on ridge of the patient were of different size presented lesions

In the laboratory examinations results, the hemoglobin value was 19.8 g/dL, the erythrocyte count was 5.98 × 106/mm3, the leukocyte count was 12,120/mm3, and the thrombocyte count was 321,000/mm3. The cholesterol and triglyceride levels were normal. Liver functional tests, renal functional tests, and thyroid hormones tests were between normal ranges. The C-reactive protein was 26 mg/dL, and the sedimentation was 2 mm/h. The brain magnetic resonance imaging (MRI), thorax tomography, bone survey, abdominal ultrasonography (USG), and urinary USG were normal. By superficial USG, multiple isoechoic hypoechoic lesions were observed among the muscle plan. The largest lesion was 13 × 10 mm. In thoracolumbar MRI, multiple massif lesions retaining peripheral contrast (the biggest was 1.7 × 1.4 cm large) has been observed under the skin muscle plans in thoracolumbar regions, between the extremities muscles, in the regions of section, at hyperintense and hypointense intravenous contrast substance injection at T2-weighted image and T1-weighted image [Figure 2].

Figure 2

In thoracolumbar magnetic resonance imaging had been observed between the underskin muscle plans in thoracolumbar regions (sagittal section)

Histopathology included varying amounts of extracellular collagen and uniform spindle cells. Cell bundles were spread into adjacent tissues. Lesional cells had central elongated nuclei and vaguely fibrillar cytoplasm. The diagnostic feature was the presence of intracytoplasmic, eosinophilic spherical inclusions [Figure 3]. The lesional cells were not nuclear atypia and mitoses. In histochemical staining, these inclusions stain the brightly purple-red rounded with mason-trichrome staining. No staining with PAS was observed. As a result of the immunohistochemical staining of the lesion biopsy, smooth muscle actin was positive; desmin, S100, and CD34 were negative. These findings were diagnosed via IDF. The patient was followed and was discharged assuming his participation to controls.

Figure 3

The plump spindle cells, uniform nuclei and scattered intracytoplasmic eosinophilic round inclusions (H and E, × 400)

Discussion

The IDF lesions may be solitary or multiple and may present as “kissing” tumors on opposing digits. The IDF are usually asymptomatic at birth, but flexion deformity of the digits may occur at birth.[1] In our patient, lesions were present at birth.

IDF has been determined on inhabitual localizations. Sungur et al.[5] have defined infantile digital fibroma in the volar face of the right pinkie at the distal interfaringial articulation. IDF rarely occurs in extra-digital sites such as the soft tissues of the arm, breast, lingual, and thigh.[6-11] Fernández-Jorge et al.[12] reported that magnetic resonance image displayed a fibromatous tumor, which locally infiltrated tendon structures. Rimareix et al.[13] reported that radiograph and the ultrasound scan are usually normal, and the magnetic resonance scan can determine the depth of invasion, in which the structures were involved. In our case, in the absence of lesions on fingers, by superficial USG, muscles and multiple isoechoic hypoechoic lesions were observed among the muscle plan. The biggest lesion was 13 × 10 mm. In thoracolumbar MRI, multiple massive lesions retaining peripheral contrast (the biggest was 1.7 × 1.4 cm large) have been observed under the skin muscle plans in thoracolumbar regions, between the extremities muscles, in the regions of section, at hyperintense and hypointense intravenous contrast substance injection at T2-weighted image and T1-weighted image.

The diagnosis is confirmed by finding numerous spindle-shaped fibroblasts that contain small, round, dense, eosinophilic cytoplasmic inclusion bodies composed of collections of actin microfilaments.[1] The diagnosis was based on the histochemical staining and histopathology findings.

Treatment of IDF contains excision, amputation, and skin graft.[14] Local recurrence after simple excision of this tumor has been reported in 75% of patients. Because the tumor does not metastasize and may regress spontaneously in 2-3 years, a course of expectant observation is advised. If functional impairment or flexion deformity of the digit becomes apparent, prompt full excision of the tumor is indicated. Kawaguchi et al.[15] and Niamba et al.[16] have described spontaneous regression tumors. Topical or intralesional steroids are used for the treatment, and different results have been described.[17] We keep our patient under observation because of the multiplicity of the lesions and because of the possibility of spontaneous regression. No medicine treatment has been given for the moment.

Conclusion

The case was presented aiming to illustrate and remind that IDF can be observed in babies without finger involvement.

What is new?

To our knowledge, the youngest case that is report in the literature.