Why is the patient itching?

A 40-year-old man who works as a labourer in a cement plant tells the doctor who provides medical cover to all the men working at the plant that he is finding it increasingly difficult to have a shower. The plant is in Karachi and the management provides hot and cold water for a shower at the start and end of each shift to reduce the incidence of skin allergies caused by the dust from the plant. He reports this in July during a routine medical checkup, and says that in the winter he stopped taking a hot shower because he developed severe itching 10 minutes later but a cold shower did not cause this. Now even the cold water causes the pruritis which is on the back, back of the legs and insides of the arms. The doctor examines his skin and can find only excoriation from where he has scratched with some lichenification but  no rash, eczema, urticarial nodules or other lesions. The doctor examines the skin between the toes and fingers and the groin but can find no lesions. The doctor prescribes Sarna lotion and an antihistamine tablet.

What is this condition and what is causing it?

This is aquagenic pruritis, usually worse with hot water but may occur with cold water as well and typically the onset is 10-15 minutes after exposure to water. Likely systemic diseases causing pruritis which may precede other clinical manifestations for several years are:

  • Hodgkin lymphoma – Itching as a primary symptom is commonly seen in patients with Hodgkin lymphoma, developing in approximately 30 percent of cases. In some patients, pruritus precedes the clinical presentation of lymphoma by up to five years and therefore can be regarded as a paraneoplastic sign. Itching is often located on the lower extremities and is occasionally accompanied with ichthyosiform skin changes. Pruritus related to Hodgkin lymphoma is often more severe in older patients and patients with more advanced disease. Symptoms may be aggravated at night. It is not related to water or taking a shower usually.
  • Polycythemia vera – Aquagenic pruritus (water-induced itching) may occur in up to two-thirds of patients with polycythemia vera. Patients frequently complain of intractable itching within minutes after contact with water. Alternatively, stinging, tingling, or burning sensations occur. The chest, back, medial upper arms, and anterior legs are common sites of involvement. Aquagenic pruritus may precede a diagnosis of polycythemia vera by several years or more. The condition has also been associated with other diseases including myelodysplastic disorders and T cell lymphomas.
  • Mycosis fungoides – Pruritus is a frequent manifestation of mycosis fungoides (cutaneous T cell lymphoma), although it is typically not present in the absence of cutaneous findings. The erythrodermic form of mycosis fungoides and Sézary syndrome are extremely pruritic. Folliculotropic mycosis fungoides has been reported to be extremely pruritic regardless of the stage of the disease. There are case reports of pruritus preceding the onset of skin findings by several years.
  • Other hematological malignancies – Patients with non-Hodgkin lymphoma may present with pruritus, but there are limited epidemiologic data on the prevalence of this symptom. Other hematologic malignancies linked to chronic pruritus include leukemia, most commonly chronic lymphocytic leukemia, as well as multiple myeloma and mastocytosis. In mastocytosis look for pigmented urticaria.
  • Gastric carcinoid – In contrast to the usually nonpruritic intermittent cutaneous flushing associated with intestinal carcinoids, the intermittent “histamine” flush associated with atypical gastric carcinoids tends to be pruritic.

What questions do you need to ask this patient?

  1. Does he have episodes of flushing, palpitation and fainting ever?
  2. Has he needed to be taken to the hospital during such an episode and needed injections of hydrocortisone? We are chasing release of reactants from carcinoid or mast cells giving an anaphylaxis like reaction.
  3. Has he ever reacted to a bee sting or wasp sting severely enough to be taken to the hospital?  This can happen in mastocytosis.
  4. Is he losing weight, feeling tired and unable to cope with his work? Think of a lymphoma, chronic lymphocytic leukemia, multiple myeloma.

How will you exclude body lice (pediculosis corporis)?

Itching is the chief complaint, although some individuals do not seem to be troubled by the infestation. Signs may be limited to linear excoriations on the trunk and neck along with postinflammatory hyperpigmentation, sometimes with thickening or lichenification along areas of the involved trunk. Close inspection will sometimes reveal hemorrhagic puncta or wheals from fresh bites. Skin changes tend to be concentrated around the waist and in the axillary folds, areas where clothing seams contact the integument. The honey-like crusting and redness characteristic of secondary staphylococcal infection may also be present. Use oral invermectin, discard or heat wash all clothes and bed linen. Also treat anyone sharing his bed or a crowded home. This patient has no skin lesions and is required to bathe frequently. So the infestation is unlikely.

Do you think this is scabies?

Scabies is an infestation of the skin by the mite Sarcoptes scabiei. Classic scabies typically manifests as an intensely pruritic eruption with a characteristic distribution. The sides and webs of the fingers, wrists, axillae, areolae, and genitalia are among the common sites of involvement. Crusted scabies, a less common variant that primarily occurs in the setting of reduced cellular immunity and is associated with a heavy mite burden, is characterized by thick scale, crusts, and fissures. The diagnosis of scabies is confirmed through the detection of scabies mites, eggs, or feces with microscopic examination. Use oral invermectin and topical permithin, invermectin or benzylbenzoate.

What workup and follow up will you advise if you do not think that this patient has pediculosis or scabies?

Record his weight now and record it every month. This is very important. All of you forget to weigh your patient in the general physical examination. Except fot the paralysed or those who are unable to get up or get out of bed please weigh your patient. The weight is important for nutritional assessment both for malnutrition and the obese specially if you wish to discuss the metabolic syndrome. If a patient has fluid retention the best way to know that your therapy is working is to record daily loss of weight and increase your diuretic accordingly. If you are treating diabetes then weight gain or loss is a major prognostic factor. Persistent weight loss in HIV/AIDS means the treatment is not effective and the disease is progressing. Please get into the habit of weighing your patient in the ward. Do it at the end of the GPE if there are more important findings. It would be unforgivable if you weigh the patient and do not check the BP or look for anemia and jaundice or lymphadenopathy. If you find an enlarged thyroid then the weight is very important.

Look for anemia, jaundice and lymph node enlargement. Check the BP. Hypertension is an important finding in Polycythemia rubra. Note the colour of his face and note down if he looks plethoric. Look for the spleen and liver. Note their sizes so that you can measure subsequent enlargement. Look for ascites. Assess the patient for a failing heart which may be precipitated: pedal edema, raised JVP, palpable liver, crackles at the lung bases, cardiomegaly and 3rd or 4th heart sounds.

You must know what you are doing, why you are doing it and what it means. You must interpret the clinical signs as you find them. That is what you are being examined for: your ability to understand what the disease is doing to the patient.

The examiner asks “Is this a cutaneous form of Lupus/SLE?

The answer is no. Prominent pruritis is unlikely in SLE.  Subacute cutaneous LE (SCLE) begins as small, erythematous, slightly scaly papules that evolve into either psoriasiform plaques (papulosquamous SCLE) or annular plaques (annular SCLE). The latter often coalesce to form polycyclic or figurative patterns. The plaques are typically erythematous with variable amounts of overlying scale. The most common sites of involvement are somewhat photodistributed and include the shoulders, forearms, neck, and upper torso. Despite a photoaggravated nature of the condition, the face is often spared. Dyspigmentation at sites of resolved SCLE is common and may resemble vitiligo. Scarring usually does not occur. Less common variants include vesiculobullous annular, poikilodermatous, erythrodermic, and erythema multiforme-like (Rowell syndrome) SCLE. Drug-induced SCLE is reviewed separately. Most patients with SCLE exhibit photosensitivity, with exacerbations of disease stimulated by sun exposure.  This patient has no skin lesions except for excoriation from scratching and does not complain of worsening of symptoms on exposure to the sun. You must be able to explain why your answer is no. Be prepared. Look up cutaneous manifestations of porphyria. Anticipate what questions can be asked.

Could this be a cutaneous manifestation of dematomyositis/myositis?

Typically we find Gottron’s papules: erythematous to violaceous papules that occur symmetrically over the extensor (dorsal) aspects of the metacarpophalangeal (MCP) and interphalangeal (IP) joints . These lesions may involve the skin between the MCP and IP joints, particularly when the eruption is prominent. They are scaly and may ulcerate. Can mimic psoriasis or lichen planus. Gottron’s sign is the presence of erythematous to violaceous macules, patches, or papules on the extensor surfaces of joints in sites other than the hands, particularly the elbows, knees, or ankles. Heliotrope eruption  on the upper eyelids, sometimes accompanied by eyelid edema, which, at times, may be quite marked. There may be facial erythema mimicking  the malar erythema seen in SLE involving the nasolabial fold, which can be helpful in distinguishing these two photosensitive midfacial eruptions. Photodistributed poikiloderma including the shawl and V signs hyperpigmentation and hypopigmentation, as well as telangiectasias and epidermal atrophy.  The cutaneous eruption of DM is  associated with significant pruritus, which distinguishes it from  photo-exacerbated eruption from that of lupus erythematosus (LE). Patients with DM may also have poikiloderma on the lateral aspects of the thighs, referred to as the “Holster sign”. It is unclear why this cutaneous manifestation occurs on this classically photo-protected site. Generalized erythroderma occurs rarely. Periungual abnormalities, the capillary nail beds in DM show vascular changes similar to those in other systemic rheumatic diseases (eg, scleroderma and SLE).  In addition, cuticular overgrowth, sometimes termed “ragged cuticles,” is characteristic and may be associated with hemorrhagic infarcts within the hypertrophic area. Changes in the scalp resembling seborrheic dermatitis or psoriasis occur in a high percentage of patients with DM showing poikilodermatous changes and with prominent scaling.  Read up calcinosis cu

Scalp involvement may result in severe burning, pruritus, and/or sleep disturbance. In addition, severe pruritus may occur in patients without visible disease.

Patients with either DM or PM (classically those with the antisynthetase syndrome) may have “mechanic’s hands,” which present with hyperkeratotic, fissured skin on the palmar and lateral aspects of the fingers. Occasionally, these changes result in irregular, dirty-appearing horizontal lines that resemble those of a manual laborer.

Now that there is a possibility of dermatomyosits pay attention to the neurological examination specially the strength of the proximal muscles. For the lower limb ask the patient to get up from a squatting position or if that is not possible to get up from a chair. Do not call this Gower sign just say that you are checking out the glutei and quadriceps and hamstrings, ask the patient to stand on one leg and then the other. For the upper limb ask the patient to raise his extended arms from his weight to the height of the shoulders, then raise them above the head in the lateral position, then to bring the arms forward and then raise them above the head, then proceed to do the motor examination as you know how.

When you are preparing for the examination read “across” subjects which can be part of a D/D or which the examiner may just ask you to test your knowledge.

The D/D here is going to be polycythemia rubra, dermatomyositis without any skin changes, cutaneous lymphoma ie mycosis fungoides all of which may present for months or years without visible skin lesions. You will keep this patient under observation for the development of photosensitivity, polycythemia, anemia and evidence of a lymphoma. SLE is a remote possibility.

What investigations will you do? That is my question. Those of you who are reading this blog may please send me an answer with reasons for the investigations. Writing “I will do routine examinations” will earn you a big failing score. No examination is routine. It is always done for a reason.




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I am a Professor of Medicine and a Nephrologist. Having served in the Army Medical College, Pakistan Army for 27 years I eventually became the Dean and Principal of the Bahria University Medical and Dental College Karachi from where I retired in 2016. My passion is teaching and mentoring young doctors. I am associated with the College of Physicians and Surgeons Pakistan as a Fellow and an examiner. I find that many young doctors make mistakes because they do not understand how they should answer questions; basically they do not understand why a question is being asked. My aim is to help them process the information they acquire as part of their education to answer questions, pass examinations and to best take care of patients without supervision of a consultant. Read my blog, interact and ask questions so that I can help you more.

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