Megha Rajput, BS
Medical Student
William Carey University College of Osteopathic Medicine
Brookshire, Texas, United States
Howard Maibach, MD
Dermatologist
University of San Francisco Department of Dermatology
San Francisco, California, United States
Patient History
A 24-year-old female sought consultation with a dermatologist due to the presence of a slow-growing superolateral knee mass. The mass, which had been progressively enlarging over a period of three years, exhibited characteristics of being mobile, firm, spherical, and devoid of tingling, radiation, or sharp pain. The patient reported minimal pain without radiation, specifically when the knee was subjected to soft external stimuli. The dermatologist suspected the patient had a lipoma or an epidermal cyst.
Treatment Plan
Upon examination, an orthopedic surgeon recommended excision of the mass under local anesthesia. The decision for surgical intervention was driven by the suspicion of the mass being attached to the bone.
Case Description:
Biopsies
‘Left knee soft tissue mass’ received on formalin is a tan, partially encapsulated, soft tissue mass measuring 2.0 x 1.6 x 1.0 cm. The exterior surface is inked blue. The specimen is serially sectioned, revealed a tan, gelatinous, well-circumcised lesion occupied the entire specimen.
Laboratory Data
Microscopic examination of the biopsied tissue revealed a well-defined proliferation of spindled cells, showcasing Verocay bodies with distinct Antoni A and Antoni B areas. Importantly, there were no identified atypical nuclei or increased mitotic activity, contributing to the characterization of the lesion as benign.
Discussions:
Diagnosis
Based on the comprehensive pathology findings, the conclusive diagnosis for the presented case is an anterior knee schwannoma. The rarity of this specific location for a schwannoma underscores the uniqueness of the patient's condition, necessitating further exploration into the clinical implications and management strategies for such atypical presentations.
Conclusions: Schwannomas, benign tumors originating from Schwann cells, are a relatively uncommon occurrence within the realm of peripheral nerve tumors. However, the manifestation of a schwannoma in the anterior knee region is an even rarer phenomenon, with only a limited number of documented cases in the existing medical literature.
