Granuloma annulare subtypes: sonographic features and clinicopathological correlation

Granuloma annulare on ultrasound: a diagnosis to consider in pediatric skin lesions

BACKGROUND

Granuloma annulare (GA) is a rare, benign, inflammatory, self-limited, granulomatous dermatosis that affects children and young adults. The most frequent clinical form is localized GA. Deep GA generally presents as painless palpable subcutaneous nodules in the lower extremities, buttocks, hands and scalp. They may have a fast-growing firm subcutaneous mass presentation, mimicking a malignant lesion which requires an imaging evaluation. Diagnosis of deep GA can be more difficult and imaging evaluation is frequently performed, ultrasound being one of the techniques used.

OBJECTIVE

To describe the US characteristics of GA in a pediatric series.

MATERIALS AND METHOD

Descriptive, retrospective, 14-year study of all pediatrics GA cases.

RESULTS

Twelve pediatric cases with GA. 66% females. The lesions were mainly distributed in the extremities: 50% in the lower extremities and 42% in the upper extremities, mostly with multiple lesions. A total of 45 lesions were analyzed, 8 superficial lesions and 37 deep lesions. On ultrasound, the superficial GA corresponded to hypoechoic poorly defined solid plaque like or nodular lesions, located in the dermal-epidermal plane. The deep GA presented as solid nodular, poorly defined hypoechoic lesions that compromised the deep subcutaneous-aponeurotic plane.

CONCLUSION

GA is an inflammatory lesion that presents as a superficial or deep palpable nodule that predominantly affects children. Superficial and deep GA present characteristic findings on US that can guide the diagnosis. The radiologist needs to know its US appearance to be able to suggest the diagnosis, especially in multiples lesions.

The epifascial cap: A typical imaging sign for subcutaneous granuloma annulare in children

Objectives

Subcutaneous granuloma annulare (SGA) is a rare, self-limiting granulomatous disease in children, commonly diagnosed by histopathology following biopsy or surgical excision. This study aimed to identify imaging clues for SGA that could expedite accurate diagnosis and avoid the need for biopsy in children.

Methods

We retrospectively analyzed complete hospital records of all children diagnosed with SGA at our institution from January 2001 to December 2020. Detailed disease history, imaging findings, management, and outcome were evaluated.

Results

We identified 28 patients (20 girls) at a median age of 3.75 (range 1-12.5 years). Ten patients presented with multiple lesions. Most lesions were located on the lower extremities (n = 26/41). Ultrasound examinations were performed on all patients, and 12 (43%) patients also received an MRI. Surgical intervention was conducted in 18 (64%) patients either by incisional biopsy (n = 6) or total excision of the lump (n = 12). In all patients who did not undergo surgery, SGA resolved spontaneously. A careful review of the MRIs led to the discovery of a characteristic imaging shape of SGA lesions: the epifascial cap with a typical broad circular base laying on the fascia, extending towards the subdermal/dermal tissue. This distinctive shape was evident in every patient in our cohort.

Conclusions

The "Epifascial Cap Sign" is a specific imaging sign for SGA, which to the best of our knowledge, helps distinguish this disease from other subcutaneous lesions. Recognition of this novel diagnostic sign combined with the historical and physical findings should enable clinicians to establish SGA diagnosis easily and diminish the need for further invasive diagnostic procedures.

Cutaneous ultrasound: key diagnostic tool for the relapse of a single eccrine spiradenoma

Eccrine spiradenoma is a rare, benign, adnexal skin tumor of the sweat gland. It is frequently solitary and presents as a small lesion in the dermal or the subcutaneous fat layer. Eccrine spiradenomas rarely progress to malignant transformation but they can relapse. Due to its rarity, there have been few reports about the sonographic appearances of eccrine spiradenoma. Sonographic findings were reported in a relapsing case of an eccrine spiradenoma, located in the deep dermal layers and hypodermis of the preauricular region in a middle-aged man. Ultrasound was very useful to suspect the relapse. Histology was correlated with the sonography and discussed the previously reported imaging findings of eccrine spiradenoma and other sweat gland tumors.

Granulomas in Dermatopathology: Principal Diagnoses - Part 2

Part 2 of this series on granulomatous diseases focuses on skin biopsy findings. Whereas the first part treated noninfectious conditions (metabolic disorders and tumors, among other conditions), this part mainly deals with various types of infectious disease along with other conditions seen fairly often by clinical dermatologists.