an 89-year - old female presented with a 3-month history of a left - sided neck lump . there was no history of shortness of breath , dysphagia , or stridor and no history of voice change . the patient had a past medical history of vascular dementia , hypertension , and b12 deficiency secondary to pernicious anaemia . there was no past medical history of thyroid disease or neck irradiation and no family history of autoimmune disease . on examination examination of the neck revealed a large firm , irregular mass in the upper pole of the left thyroid lobe with a background of multinodular goitre . the lump measured 6.1  cm    5.5  cm with calipers on presentation . there was no evidence of lymphadenopathy and the trachea was central with no signs of stridor . initial assessment was suggestive of lymphoma or poorly differentiated carcinoma . in order to increase diagnostic accuracy , iu / l ) with a thyroid peroxidase antibody ( tpa ) of 557  iu / ml ( 050  iu / ml ) and free t4 of 12.5  pmol / l ( 1126  pmol / l ) . full blood count , liver function tests , and urea and electrolytes were all in the normal range . this showed a heavy plasma cell infiltrate and admixed b- and t - lymphocytes ( figure 1 ) . the plasma cell infiltrate was polyclonal ( figure 2 ) and expressed cd79a , cd138 , and mum-1 . the histological findings were therefore consistent with a plasma cell granuloma of the thyroid with underlying hashimoto 's thyroiditis . due to patient frailty and comorbidities , the lump measured 4.5  cm    3  cm 10 months after presentation and 8 months following start of treatment with thyroxine . plasma cell granuloma of the thyroid gland is rare with only 16 previously reported cases . it predominantly affects women with the majority of cases reporting patients over the age of 35 years . plasmacytoma of the thyroid is more common and the two can be differentiated histologically by assessing for clonality . plasma cell granuloma ( pcg ) is well documented in the literature , first being described in 1973 by bahadori and liebow . it is a nonmalignant lesion characterised by proliferation of polyclonal plasma cells with varying degrees of myofibroblastic proliferation . lesions of this type are mainly found in the lungs with other recorded cases occurring in the liver , stomach , pancreas , bladder , and kidney . hurthle cell metaplasia found on histology has been documented in some cases [ 810 ] of pcg of the thyroid but this is not universal . macroscopically , there are also some variations in the literature but the lesions are usually firm with a white / grey colour . it has been suggested that it may be secondary to a chronic inflammatory process causing abnormalities of plasma cell differentiation . many of the cases of thyroid plasma cell granulomas demonstrate an association with an autoimmune disease such as hashimoto 's thyroiditits and diabetes mellitus [ 1014 ] . this is largely anecdotal and , although there is no strong evidence to link the two disease processes , it can be supported by evidence of the cellular infiltrate expressing antithyroid peroxidase antibodies and response to immunosuppressant medications . treatment of these lesions varies in the literature with the majority of patients undergoing some form of surgical intervention with either total / subtotal thyroidectomy or lobectomy ( table 1 ) . corticosteroid usage and other immunosuppressive therapies such as cyclophosphamide and azathioprine have also been used to treat these lesions with some degree of improvement . in our case , we have shown that these benign lesions can resolve spontaneously without the need for unnecessary surgery or medications with potentially significant side effects . we do , however , appreciate that surgical intervention may be a necessity in a case of a large , rapidly increasing nodule that is compromising a patients airway or is associated with significant symptoms . however , if pcg is confirmed histologically , for example , on core biopsy as in our patient , with no debilitating symptoms , it is reasonable to observe these cases without any intervention either surgical or medical other than treatment of any underlying thyroid dysfunction .
introduction . we present a case of an 89-year - old female who attended our surgical endocrine clinic with a 3-month history of a left - sided neck lump . 
 there was no past medical history of thyroid disease . 
 methods . following examination and further investigation , including core biopsy , a diagnosis of plasma cell granuloma of the thyroid was made . 
 biochemical testing of thyroid function and thyroid peroxidase antibody was in - keeping with an associated hashimoto 's thyroiditis . 
 results . 
 the patient was treated conservatively with thyroxine and regularly seen in clinic . 
 tsh levels improved and the lump showed signs of regression . 
 conclusion . 
 plasma cell granuloma of the thyroid is rare with only 16 previously reported cases . 
 we present a new approach to management without the use of surgery or steroids . 
 the literature is reviewed comparing clinico - pathological features and management of other reported cases .