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Herein we describe a case of periosteal ganglia presenting as asymptomatic subcutaneous nodules on the anterior lower extremity.
A woman in her 40s presented with a 3-month history of asymptomatic grouped subcutaneous nodules on the left shin. The lesions appeared spontaneously without any preceding trauma. Physical examination of the left anterior lower extremity revealed grouped, soft, immobile nodules without overlying epidermal changes (Figure 1A). A punch biopsy of a characteristic nodule induced extrusion of a gelatinous, clear, myxoid material (Figure 1B). Histopathologic findings revealed normal skin and subcutaneous tissue with deep soft-tissue mucinous debris that was separated from the overlying skin. Magnetic resonance imaging of the left lower extremity showed a lobulated cystic lesion overlying the anterior tibia, with no communication with the knee joint (Figure 2). The absence of diffusion restriction ruled out an underlying abscess. No underlying bony abnormalities were identified. These findings confirmed a diagnosis of a periosteal ganglion of the tibia. The patient was referred to the orthopedic surgery service, where she declined standard surgical excision and instead opted for aspiration with subsequent compression. At the time of writing, she continued to be monitored through the orthopedic surgery service.
A, The ganglia presented as grouped and immobile nodules without overlying epidermal changes on the left anterior lower extremity. B, A punch biopsy of a nodule on the left lower extremity demonstrated a periosteal ganglion of the tibia, with extrusion of a gelatinous, clear, myxoid material.
Magnetic resonance imaging of the left lower extremity demonstrated a lobulated cystic mass overlying the anterior tibia.
Periosteal ganglia are uncommon single or multiloculated subcutaneous cystic nodules. These lesions are rarely encountered by dermatologists and are usually seen in the orthopedic setting. Although described mainly in men, these lesions also have been reported1,2 in children. Periosteal ganglia typically involve the tibia, but reports2-4 have also described involvement of the medial malleolus, femur, ilium, radius, and ulna. Duration before presentation varies from several weeks to years.1 Lesions can be asymptomatic or tender, and a history of trauma is variable.3
Mucoid degeneration of the periosteum is the most frequently proposed pathogenesis for the formation of periosteal ganglia.1-6 Fibroblasts are thought to form intercellular mucin, which coalesces to form cystic lesions. Accumulation of mucoid material compresses the surrounding tissue, thereby inducing further fibroblast proliferation, collagen production, and ultimately an encapsulating fibrous wall.4 The central cystic contents are composed of an acellular mucinous or gelatinous fluid.4 Although communication with the underlying joint space has not been reported, cases have shown3,5 varying degrees of underlying cortical erosion with scalloping and spiculated bone reactions. Choi and colleagues4 described a case with an underlying interosseous component. However, as in our patient, these cysts frequently have no underlying connection to the cortical bone.
Several imaging modalities to evaluate periosteal ganglia have been described. Plain radiographs, although helpful in detecting underlying bony changes, are nonspecific and do not differentiate pretibial ganglion cysts from other surface tumors.3 Computed tomography is helpful in further discerning characteristics of the soft-tissue mass, but magnetic resonance imaging is the modality of choice.3 Magnetic resonance imaging demonstrates a homogeneous signal intensity, which appears isointense to muscle on T1-weighted images and has a high signal intensity when compared with fat on T2-weighted images.3,5
Definitive treatment of periosteal ganglia is by surgical excision. Some authors1-3 recommend excising an adjacent margin of normal periosteum to prevent recurrence. Although recurrence after surgical excision has been described,1,3 this may represent continued mucoid degeneration rather than incomplete excision.
The clinical differential diagnosis for pretibial subcutaneous masses or nodules is broad and includes erythema nodosum, nodular pretibial myxedema, subcutaneous sarcoidosis, periosteal chondroma, parosteal lipoma, subperiosteal hematoma, subperiosteal abscess, periosteal aneurysmal bone cyst, chondromyxoid fibroma, or periosteal osteosarcoma.1-3,5 Although uncommon and rarely encountered by dermatologists, periosteal ganglion cysts remain an important condition to consider in the differential diagnosis of subcutaneous pretibial lesions. This case highlights the need for dermatologists to recognize this uncommon diagnosis to facilitate appropriate workup and referral.
Corresponding Author: Nkanyezi N. Ferguson, MD, Department of Dermatology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr, Iowa City, IA 52242 (email@example.com).
Published Online: February 19, 2014. doi:10.1001/jamadermatol.2013.6352.
Conflict of Interest Disclosures: None reported.
Ferguson NN, Asarch A, Tschetter AJ, Stone M. Periosteal Ganglia Presenting as Subcutaneous Nodules on the Tibia. JAMA Dermatol. 2014;150(6):663–664. doi:10.1001/jamadermatol.2013.6352
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