Gardner Fibroma with Localized Hypertrichosis without Adenomatous Polyposis Coli Gene Mutation
Gardner fibroma (GAF) is a rare benign soft tissue tumor that is often associated with familial adenomatous polyposis (FAP), a condition linked to mutations in the adenomatous polyposis coli (APC) gene. Both GAF and FAP are components of Gardner syndrome (GS), which is characterized by a triad of intestinal polyposis, soft tissue tumors (including GAF and desmoid tumors), and osteomas. This case report presents a unique instance of sporadic GAF in a 29-year-old Chinese man without APC gene mutations, accompanied by localized hypertrichosis and a tubular adenoma in the sigmoid colon. The findings underscore the significance of GAF as a sentinel marker for gastrointestinal and bone abnormalities, even in the absence of APC mutations.
The patient presented with a painless mass on the right lateral thigh that had been present for five years. There was no significant family history of similar conditions. Physical examination revealed a soft, well-circumscribed brown-colored mass measuring approximately 2 cm × 2 cm, with 28 terminal dark black hairs uniformly distributed over the surface. Serum analysis showed an elevated level of neuron-specific enolase at 20.4 ng/mL (normal range: 0–16.3 ng/mL). Gray-scale ultrasound imaging identified a superficial, ill-defined hypoechoic nodular area measuring 21 mm × 6 mm. The mass exhibited multiple strips of hypoechogenicity and punctate hyperechogenicity. Color power Doppler analysis revealed a twinkling artifact within the nodule.
Histopathologic examination of the mass demonstrated hyperkeratosis and local atrophy of the epidermis. The dermis showed a hypocellular proliferation of haphazardly arranged coarse collagen fibers with inconspicuous spindle cells and locally degenerated hyaline. The collagen fibers were observed to form around adipose tissue lobules. Notably, an increased number of hair follicles was noted deep in the dermis. Immunohistochemical staining was negative for β-catenin, cyclin-dependent kinase D1 (cyclin-D1), cellular myelocytomatosis (C-myc), cluster of differentiation 34 (CD34), S-100, and fibroblast growth factor 3.
Whole-body bone imaging revealed no abnormalities, and abdominal ultrasound excluded the presence of intra-abdominal fibroma or desmoid tumors. However, a tubular adenoma measuring 0.5 cm × 0.5 cm with low-grade dysplasia was identified in the sigmoid colon. Genetic testing was performed on peripheral blood samples from the patient and his parents. All 15 exons and flanking introns of the APC gene were amplified by polymerase chain reaction, but no mutations were detected.
GAF typically presents as painless, single or multiple subcutaneous masses, most commonly located on the back, paraspinal region, and upper extremities. The size of these masses generally ranges from 0.5 to 2.5 cm. While GAF is often associated with APC mutations, it can also occur sporadically without such genetic alterations. Previous studies have shown that GAFs with positive APC mutations tend to be multifocal and larger, often making complete resection challenging. In contrast, sporadic GAFs without APC mutations are usually resectable and less aggressive.
The histopathologic diagnosis of GAF is based on the presence of formless sheets of thick, haphazardly arranged collagen bundles interspersed with fibroblasts. The tumor exhibits a plaque-like growth pattern, infiltrating and entrapping surrounding structures. Immunohistochemical staining typically shows reactivity for β-catenin, cyclin-D1, C-myc, and CD34. Overexpression of β-catenin and cyclin-D1 is often driven by abnormal APC gene activity. Mutations in the APC gene can lead to GS, FAP, or GAF. However, in rare cases, sporadic GAF without APC mutations may still be associated with FAP, highlighting the importance of GAF as a sentinel marker for internal organ and bone abnormalities.
This case report also highlights the presence of localized hypertrichosis as a unique manifestation of GAF. The increased number of hair follicles observed in the dermis suggests a potential relationship between fibrous proliferation and hair follicle formation in GAF. This finding warrants further investigation to elucidate the underlying mechanisms.
In conclusion, patients diagnosed with GAF should undergo comprehensive examinations, including genetic mutation testing, to identify potential gastrointestinal and bone abnormalities. The presence of GAF, even in the absence of APC mutations, should prompt clinicians to consider the possibility of associated conditions such as FAP. This case underscores the importance of GAF as a sentinel marker and highlights localized hypertrichosis as a unique clinical feature that may provide insights into the pathogenesis of this rare tumor.
doi.org/10.1097/CM9.0000000000000383
Was this helpful?
0 / 0