DIAGNOSTIC APPROACH TO SUBCUTANEOUS NODULES IN PATIENTS WITH NEUROENDOCRINE TUMORS TREATED WITH DEPOT SOMATOSTATIN ANALOGS

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 303-321-Cancer in Endocrine Tissues
Bench to Bedside
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-321
Javier Riveiro*1, Amalia Paniagua2, Begoña Cortina1, Javier Fraga1, Sara Ibañes1, Esteban Daudén1 and Mónica Marazuela1
1Hospital Universitario La Princesa, Madrid, Spain, 2Hospital Universitario Infanta Cristina, Parla, Spain
Introduction. Subcutaneous nodules are frequently identified on routine abdominal computed tomography (CT) scans in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs) receiving depot somatostatin analog (SSA) therapy and are commonly labeled as metastases. On sonographic evaluation, subcutaneous metastases are typically hypoecogenic, present a polycyclic shape and multiple feeding vessels.

Material and methods. We performed a prospective study at a university hospital and studied 12 patients with GEP-NETs and possible subcutaneous metastases detected on routine abdominal CT scans to determine the differential characteristics of subcutaneous nodules secondary to administration of SSA. Patients underwent high-resolution and color Doppler sonography, cytology (5 patients), and biopsy (4 patients). Mean group values were compared using one-way ANOVA or a Kruskal-Wallis test. Strength of association was evaluated with Spearman’s correlation test.

Results. Mean age was 61.3 ± 11.9 years. Five patients were male and 7 were female. Median number of nodules was 6 ± 5 per patient. Three patients were on octreotide LAR, 7 lanreotide Autogel, and 2 had received both SSA. CT scan findings were nonspecific: all nodules had poorly defined borders with hazy changes in the adjacent subcutaneous fat. Sonography revealed a different pattern from subcutaneous metastases and showed a correlation between echogenicity of the nodule and time of administration of SSA: a hyperechoic pattern was found in recent injections (less than 3 months after the depot injection) (p<0,05) and a hypoechoic pattern in long-term injections (more than 3 months) (p<0,05). Hypoechogenic lesions were frequently surrounded by a characteristic hyperechoic peripheral rim with decreased transmission. This rim was lost in long-standing nodules. On Color Doppler only mild peripheral vascularization was found in hypoechoic lesions. Cytology demonstrated characteristic acellular proteinaceous material. Biopsy showed a granulomatous reaction with epithelioid cells and foreign body giant cells around the acellular proteinaceous material.

Conclusions. Although CT scans are nonspecific, sonography is very useful for the differential diagnosis of subcutaneous nodules secondary to treatment with SSA. Cytology is a minimally invasive procedure with considerable diagnostic potential. Biopsy should be reserved for rare cases in which a definitive diagnosis has not been reached.

(1) Giovagnorio F, Valentini C, Paonessa A 2003 High-resolution and color doppler sonography in the evaluation of skin metastases. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine 22:1017-1022; quiz 1023-1015 (2) Debono M, Hon LQ, Bax N, Blakeborough A, Newell-Price J 2008 Gluteal nodules in patients with metastatic midgut carcinoid disease treated with depot somatostatin analogs. The Journal of clinical endocrinology and metabolism 93:1860-1864 (3) Rideout DJ, Graham MM 2001 Buttock granulomas: a consequence of intramuscular injection of Sandostatin detected by In-111 octreoscan. Clinical nuclear medicine 26:650

Nothing to Disclose: JR, AP, BC, JF, SI, ED, MM

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: This work was supported by grants to Dr. M. Marazuela from FISS 07/1119.
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