the adenoma is solitary in 8590% of patients , while others have multiple adenomas or parathyroid hyperplasia .
accurate preoperative localization is essential for good surgical outcome , and inability to locate the adenoma in an ectopic gland may delay the diagnosis .
nuclear imaging accurately localizes the tumor in more than 90% of cases , obviating the need for advanced imaging modalities .
rarely , patients present with localization failure posing a great challenge to the treating endocrinologist and operating surgeon .
we report the use of a novel imaging method leading to successful outcome in a patient of primary hyperparathyroidism with failed first surgery .
a 54-year - old lady presented with body pains and muscle aches for 1-year duration to a peripheral hospital . investigations revealed high serum calcium ( 11.6 mg / dl ) , low phosphorus ( 2.6 mg / dl ) , elevated alkaline phosphatase ( 677 u / l ) and intact parathyroid hormone ( ipth ) of 116 pg / ml ( normal 10 - 65 pg / ml ) .
sestamibi scan revealed right inferior parathyroid adenoma , and she was diagnosed as a case of primary hyperparathyroidism .
she underwent adenomectomy along with thyroidectomy and showed no features of hungry bone syndrome postoperatively .
there was no confirmation of parathyroid adenomectomy by using intraoperative pth levels or by frozen section of the removed tissue .
her clinical symptoms persisted after surgery and histopathological examination of the specimen removed showed thyroid tissue with no evidence of parathyroid adenoma .
she reported to us after 6 months of initial surgery with persisting complaints of body aches and myalgia .
her clinical examination was unremarkable , with a normotensive blood pressure , and well - healed scar in the neck .
serum biochemistry revealed elevated calcium ( 10.8 mg / dl ) , low phosphorus ( 2.8 mg / dl ) and elevated alkaline phosphatase ( 280
bone mineral density estimation revealed a t - score of -2.2 at hip joint and z - score of -2.3 .
serum 25 hydroxy vitamin d level was 22 ng / l and parathyroid hormone was elevated ( ipth-140 pg / ml ) .
localization with sestamibi scan revealed right inferior parathyroid adenoma with no tracer uptake in thyroid bed [ figure 1 ] .
abdominal sonography showed normal renal parenchyma and ultrasonography neck and plain ct neck did not show parathyroid adenoma .
tc 99 m sestamibi scan showing right inferior parathyroid adenoma in view of past history of failed surgery , tc 99 m sestamibi single photon emission computed tomography ct ( spect ) was done for precise localization of the adenoma prior to re - exploration .
it revealed an ectopic parathyroid adenoma , located suprasternally in the pretracheal region on right side [ figure 2 ] .
histopathological examination of the specimen confirmed the parathyroid adenoma . during last follow - up , 1 year after second surgery the patient is free of all symptoms and had normal serum calcium , phosphorus and alkaline phosphatase values .
sestamibi emission computed tomography ct showing parathyroid adenoma pretracheal in location ( coronal and sagittal views )
the disease is detected during asymptomatic stage in developed countries , while we encounter the advanced spectrum of the disease with severe metabolic bone disease .
precise localization is important to prevent further delay in definitive therapy after biochemical confirmation of the diagnosis .
parathyroid glands are derived from pharyngeal pouches ( superior parathyroid glands from 4 and inferior from 3 pouch ) with subsequent caudal migration .
the modalities available for precise localization of a parathyroid adenoma are palpation , ultrasonography ( usg ) , ct , mri , nuclear scintigraphy , and combination of these tests .
ultrasonography is useful for its wide availability , convenience , cost and a guiding tool for the surgeon before surgery .
however , the sensitivity and specificity of usg reported was 73% and 100% , respectively .
ct and mri scans provide excellent spatial resolution but often miss a small parathyroid adenoma .
this is recommended mostly in cases of failed surgery , recurrent disease and when planned for a limited surgical exploration .
immediate imaging reveals the tracer uptake in both thyroid and parathyroid gland along with adenoma but the adenomatous tissue shows retention of the tracer in delayed images .
spect scan is an advance in radionuclide studies with a three - dimensional ( 3-d ) reconstruction , further increasing the sensitivity for adenoma localization .
spect scan , with its 3-d capability , combined with ct images , is very helpful in directing the surgeon particularly in recurrent or residual hyperparathyroidism .
recent reports suggest that spect / ct is superior to spect scan alone for localization of parathyroid adenoma with nodular goiter , distorted neck anatomy and those with ectopic parathyroid glands .
to conclude , our patient had an ectopic parathyroid adenoma resulting in failed initial surgery .
use of a novel imaging modality like spect helped in accurate localization of the adenoma prior to repeat surgical exploration .
 primary hyperparathyroidism often presents with protean manifestations , resulting in delayed diagnosis . at times , aberrant 
 development and migration of the gland leads to ectopic location leading to problems in localization . 
 judicious use of combination methods of localization is recommended in treatment failure or recurrent disease . 
 we report the use of single photon emission computed tomography - ct in precise localization of parathyroid adenoma in a patient with failed initial surgery . 
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