Infantile digital fibromatosis. Immunohistochemical and ultrastructural observations of cytoplasmic inclusions

Infantile Digital Fibroma: A Rare Fibromatosis

Infantile digital fibroma is a rare benign lesion that usually occurs during the first 2 years of life. It can be multiple, but it is usually a single lesion. If it grows large enough it can cause joint deformities or interfere with everyday activities. Microscopically, the neoplastic cells usually have inclusion bodies that are best highlighted with a Masson trichrome stain but can often be seen on hematoxylin-eosin staining. Treatment for this entity is usually watchful waiting because of its ability to spontaneously regress, but excision is recommended if the lesion is symptomatic. More recently, fluorouracil or injectable steroids have shown great promise in inducing regression without the complications that accompany surgery.

A range of histologic findings in infantile digital fibromatosis

Infantile digital fibromatosis is a benign proliferation of myofibroblasts with characteristic eosinophilic intracytoplasmic inclusion bodies. Clinically, patients present in the first several years of life with asymptomatic, smooth, flesh-colored nodules located on the dorsal or lateral aspect of the fingers or toes. The lesions have a tendency for spontaneous regression and recur over 60% of the time following excision. Observation is often recommended, while surgery is reserved for cases of rapid growth or functional impairment. We report three patients, ranging in age from 8 months to 8 years, with infantile digital fibromatosis. All three patients presented with nodules on the hands or feet and all shared histologic findings of spindle cells with characteristic inclusion bodies. Pathologic features ranged from a haphazard arrangement of spindle cells with few inclusion bodies and numerous lymphocytes to a well-organized arrangement of spindle cells with abundant inclusion bodies and rare lymphocytes. All three patients underwent excision for diagnosis or treatment of their tumors with two of the patients experiencing a recurrence.

Infantile digital fibromatosis

The authors report a case series on four patients with infantile digital fibromatosis located on pedal digits. Surgical excision was performed in all cases, with no evidence of recurrence. It is a rare form of juvenile fibromatosis, which presents on the fingers and toes of infants and children. Conservative treatment is recommended by authors owing to the benign nature of the lesion and its tendency to regress, and reports of recurrence after surgical intervention. We believe that surgical excision of lesions in this condition, however, remains an appropriate recommendation for the management of this rare entity.

Actin inclusions in stromal cells of fibroepithelial tumor of breast: immunohistochemical and ultrastructural studies

An uncommon occurrence of actin inclusions in the stromal cells of a benign fibroepithelial tumor of breast is reported. Histologically, many of the stromal cells contained round and eosinophilic intracytoplasmic inclusions identical to those seen in inclusion body fibromatosis. Ultrastructurally, these inclusions represented dense spherical clumps of microfilaments derived from rough endoplasmic reticulum. The literature was reviewed and follow-up data showed that the clinical course of these morphologically distinctive benign fibroepithelial tumors was relatively indolent if completely excised, in contrast to inclusion body fibromatosis, which commonly recurs. The pathogenesis may be related to abnormal production of truncated actin filaments or alteration in microenvironment.

Basal cell carcinoma with hyaline inclusions

A 69 yr old man had a 4 mm basal cell carcinoma completely excised from the chin. Numerous hyaline cytoplasmic inclusions were contained within the tumor cells. The inclusions stained intensely red with Masson's trichrome, and immunocytochemically there was prominent rim labelling for keratins (bovine, callus and AE1/3) and muscle-specific actin, the latter more faintly decorating the centre of some inclusions. The inclusions were negative for antibodies to cytokeratin Cam5.2, epithelial membrane antigen (EMA), vimentin, S100, neurofilaments, glial fibrillary acidic protein (GFAP) and carcinoembryonic antigen (CEA) and there was no post Congo red apple green birefringence to indicate amyloid. Ultrastructure indicated the inclusions were composed of proteinaceous material surrounded by a defined rim of tonofilaments in cells showing no degenerative features. The findings suggested aberrant tumor cell keratinization. Familiarization with this rare variant of a common cutaneous carcinoma will alleviate diagnostic difficulties that may arise, particularly in superficial tumor curettage.

Fine-needle aspiration cytology in fibromatoses

Fine-needle aspiration (FNA) cytology was performed in seven cases of fibromatosis of variable types with tumorous clinical presentation. These included: four cases of musculoaponeurotic fibromatosis, two in posterior neck muscles, one in anterior neck muscles and one in intercostal muscles; one case of fibromatosis of the breast; and two cases of fibromatosis colli in neonates. In all cases the specimens contained connective tissue with many fibroblast-like cells, lacking features which could indicate a malignant lesion. The findings in these cases indicate that, although by FNA cytology in fibromatoses a specific diagnosis for each pathologic entity may not be easily reached, in the proper clinical setting the cytologic findings can be of sufficient relevance to offset the need for an open tissue biopsy, where there are valid reasons against a surgical intervention.

Lingual localization of an inclusion body fibromatosis (Reye's tumor)

This report illustrates a lingual localization of an inclusion body fibromatosis, the so-called Reye tumor or infantile digital fibromatosis (IDF). The light microscopic features were identical to those found in IDF, showing eosinophilic perinuclear inclusions located in spindle-shaped cells arranged in interlacing fascicles. The immunocytochemical and ultrastructural findings suggested a fibroblastic and/or myofibroblastic nature of the proliferative cells. However, the inclusions in our case were strongly stained with vimentin and their ultrastructural appearance was in keeping with intermediate filaments. These findings have never been described in other reports of fibromatosis. Whereas most reviews state that IDF occurs exclusively on the digits, this unique case describes its possible occurrence in the tongue.

Fibroblastic-myofibroblastic tumors in children and adolescents: a clinicopathologic study of 108 examples in 103 patients

A review of over 900 soft tissue tumors in children and adolescents revealed 108 fibroblastic-myofibroblastic tumors in 103 patients from newborn to 20 years of age, which had been accessioned in a 25-year period. Based on clinicopathologic criteria, 82 (76%) were regarded as benign, 14 (13%) as borderline, and 12 (11%) as malignant. The average age at diagnosis for the entire series was 7 years with a male/female ratio of 1.8:1. The most frequent topographic site was the extremities (48, 44%), followed by the trunk (31, 29%) and the head and neck region (27, 25%). Virtually 50% (51 tumors) of cases were diagnosed during the first year of life, and 73 (71%) occurred in the first decade. The known recurrence rate was 16% (17 cases). Fibromatosis of various subtypes accounted for 95% of the histologically benign group. Infantile myofibromatosis was the most frequent form of fibromatosis, followed by aggressive (desmoid) fibromatosis (20 cases, 19%). Ninety percent of infantile myofibromatoses were diagnosed in the first year of life. In contrast, 70% of aggressive fibromatoses occurred in the second decade. Associated conditions included familial desmoid fibromatosis, Gardner syndrome, and previous surgery. The borderline category was represented by the 14 (13% of the series) congenital-infantile fibrosarcomas. All of the 14 (13%) malignant tumors were classic adult-type fibrosarcomas that occurred only in later childhood and adolescence. Fibromatosis colli, fibrous hamartoma of infancy, juvenile nasopharyngeal angiofibroma, Dupuytren-type fibromatosis, infantile digital fibromatosis, juvenile aponeurotic fibroma, unclassified fibromatoses, and fibroma of tendon or nerve sheath constituted the remaining cases.

Infantile digital fibromatosis. Immunohistochemical and immunoelectron microscopic studies

A typical case of infantile digital fibromatosis (IDF) was studied with antibodies raised against actin, vimentin, desmin and several species of cytokeratin. Strong reactions were observed for desmin, cytokeratin and CK-5, and moderate reactions for vimentin and actin. The diagnostic intracytoplasmic inclusion bodies within the tumor cells were ultrastructurally composed of aggregations of dense microfilaments. Immunoelectron microscopy showed that these filament aggregations are positively stained with anti-actin antibody. From these results, we suggest that the large tumor cell of IDF is a myofibroblast and may originate from or differentiate toward vascular smooth muscle cells, because only this type of smooth muscle can coexpress desmin, vimentin and cytokeratin.

Recurrent digital fibromatosis of childhood

Recurrent digital fibromatosis is a rare, benign fibrous growth of childhood. The condition, which features rapid growth and local recurrences, may be mistaken for a malignant tumor. A case report is presented.

A case of infantile digital fibromatosis showing spontaneous regression

A case of infantile digital fibromatosis (IDF) in a 3-year-old girl is reported. Two tumours were present on the left fourth toe and one over the lateral aspect of the left heel. Histological examination revealed that the tumor cells contained intracytoplasmic inclusion bodies, characteristic for this condition. The tumours showed spontaneous regression without therapy.

Intracisternal paracrystalline serpigenous inclusions: a marker of disordered fibroblastic proliferation

Three young children with characteristic fibroblastic tumors are presented. These comprised one case each of congenital fibrosarcoma, dermatofibrosarcoma protuberans, and fibrous hamartoma of infancy. Ultrastructural examination in each tumor revealed the presence of a peculiar intracisternal paracrystalline material that exhibited transverse periodicity between 18 and 22 nm. Elongated profiles lying within rough endoplasmic reticulum had a serpigenous outline. It is thought that this material is related to procollagen or its precursors and its presence may signify disorders of fibroblastic proliferation that may occur in fibrous tumors.