Sir,A 67-year-old male with no premorbid illness presented to us with generalized itchy lesions of 20-days duration associated with drowsiness, dizziness and loss of appetite. He had cold extremities with rectal temperature of 95 F. Pulse rate, blood pressure and respiratory rate were 56/minute, 86/56 mmHg and 16/min, respectively. There was generalized hyperpigmentation and thickening of skin with loss of body hair. We diagnosed him as chronic erythroderma with hypothermia. Baseline investigations were normal except for hypoglycemia (40 mg/dL) and hypoalbuminemia (1 gm/dl). ECG showed Osborn J waves, which are seen in mild hypothermia. Patient was passively warmed and given intravenous prewarmed dextrose normal saline, fresh frozen plasma and antibiotics along with ionotropic support. Thyroid function tests showed features of primary hypothyroidism (TSH 51.9 IU/ml, T3 normal, T4 decreased, 3.3 mg/dl). Patient was started on thyroxine. In 72 hours, patient's sensorium improved, oral temperature rose to 98 F and repeat ECG showed normal sinus rhythm. Histopathology of skin showed a hyperplastic irregularly acanthotic epidermis with follicular plugging and elongated branching rete ridges. Dermis showed periadnexal and perivascular lymphohistiocytic infiltrate with pigment incontinence, suggestive of dermatitis. He was treated with emollients and tapering course of oral prednisolone. Subsequently he developed herpes zoster and inguinal abscess. In addition as he had obstructive urinary voiding complaints a urology consultation revealed a firm, enlarged prostate with a prostatic biopsy specimen revealing adenocarcinoma. The prostate specific antigen level was markedly elevated. Bilateral orchidectomy and transurethral resection of the prostate was done. Skin condition and pruritus has significantly improved at 2 months’ follow-up.Paraneoplastic erythroderma occurs as a response to solid and hematological malignancies, characterized by dramatic increase in the epidermal turnover rate leading to erythema and scaling involving more than 90% body surface area, and impaired cutaneous functions like barrier function and thermoregulation. In hypothermia, the body temperature falls to an abnormally low level, incompatible with normal metabolism and functions. Other common causes for hypothermia include hypothyroidism, low environmental temperature and drug overdosage with phenothiazines, ethanol and sedative hypnotics.[1]Erythroderma can predate, accompany or postdate the detection of malignancy. Hypothermia in erythroderma has been previously described and is seen in approximately 1% cases. Hypothermia can be classified according to severity as mild (90-95 F), moderate hypothermia (82-90* F) and severe (<82*F). Our patient had both erythroderma and hypothyroidism as contributing factors for his mild hypothermia.Heat loss in erythroderma accompanies a defective barrier and impaired vasoconstriction along with decreased shivering reflex, further loss of body heat occurs via evaporation of oozing liquid from the surface. Normally 25% of the heat loss is by evaporation, but in extensive skin lesions, it increases. The increased transepidermal loss[2] and increased blood flow lead to heat loss by radiation, conduction and evaporation compounded by defects in vascoconstriction and activation of cold receptors.[3] Our patient possibly developed erythroderma as a paraneoplastic response to the prostatic malignancy. Hypothyroidism was later detected which was a major contributor for hypothermia. The role of thyroid hormone in thermogenesis is well known. In hypothyroidism, hypothermia is secondary to peripheral vasoconstriction.[4] Moreover, myxoedemic coma is a potentially fatal complication of hypothyroidism precipitated by any physical stress or illness and results in an altered mental status, hypothermia, bradycardia, hypercarbia and hyponatremia.[5]