Diagnosing And Treating Distinctive Pink Papules On The Ankle

There are hundreds of dermatologic disorders that can occur on the feet and lower extremities. Additionally, considering all the possible variables in host resistance and genetic variations as well as acute, subacute and chronic appearances, there are actually thousands of clinical diagnoses to take into account when one confronts a skin disorder. Morphologic description and site predisposition can help to generate and refine the differential list.

As exemplified with the following patient, recognizing a distinctive pattern can often make the clinical diagnosis a lot easier.  

A friendly, gregarious 78-year-old female presents for foot care and is unaware of the distinctive patterns of pink papules on her ankles. The non-pruritic pink papules are proximal to her sock tops and distal to her pant legs. The doctor asks the patient if there is a cat or dog at home. “No,” the puzzled patient responds. The doctor suggests that the lesions could be flea bites but the patient also denies being bitten by fleas.

Key Questions To Consider

1. What is your diagnosis of this condition?
2. What are the key characteristics of this condition?
3. How can patients prevent this condition?
4. What is the suitable treatment?

Answering The Key Diagnostic Questions
1. Bedbugs
2. The “breakfast, lunch and dinner pattern”
3. Do a careful visual inspection of hotel linens and mattress cords. Place luggage on a luggage rack and away from the bed. Carefully examine “used” items, such as garage sale items or items (especially bedding) from resale shops for bedbugs or bedbug feces.
4. Wash all insect bites with soap and water. It is fortunate that most bedbug bites do not cause symptoms. Reduce local edema with ice or a cold pack. For symptomatic relief, topical hydrocortisone, calamine or pramoxine can help to decrease pruritus.

Differentiating Bedbug Bites From Other Conditions
Asking about flea bites may be an acceptable way to help prepare the patient for the suspected diagnosis of bedbug infestation. Besides flea bites, consider mosquito bites and excoriated winter itch. Pet owners are usually well aware of fleas on their pets. Mosquito bites are itchier and generally occur with evening outdoor exposure. Dry air and older age or diabetes are more consistent with winter itch.

Asteatotic eczema is usually accompanied by linear excoriations and not the characteristic “breakfast, lunch and dinner” pattern of bedbug bites. This characteristic arrangement of several closely grouped papules represents capillary punctures of the feeding bedbugs. Some patients could inadvertently expose caregivers if their bedbugs accompany them to your office in the patient’s clothing. During the day, bedbugs normally stay at home in bedding.

Pertinent Insights On Bedbugs
Bedbugs are arthropods that generally feed preferentially on human blood, causing pruritic papules that can lead to excoriation and subsequent ulcerations and skin infection. The bugs are attracted by the carbon dioxide signature of humans but can feed on cats, dogs, birds or other animals when a human meal is not available. They often infest homes, colonizing clothing and bedclothes. Although they have vestigial wings, the wings are nonfunctional as bedbugs cannot fly. Bedbugs belong to the insect family Cimicidae. Cimex lectularius and C. hemipterus are the two species of bedbugs that most commonly affect humans.

Bedbugs only feed on blood and actually do not live on patients, but stay nearby on beds and or carpets. They feed intermittently on blood and have an average lifespan of six to 12 months.¹ Since they do not actually live on a host patient, bedbugs are technically not true parasites. Adult bedbugs are about 5 to 7 mm while juvenile bedbugs may be as small as 1.5 mm. They have six legs, widely spaced eyes and typically have a flat, red-brown, oval body with a segmented abdomen. Their abdomen has 11 segments that expand during feeding, turning the bedbug from reddish brown to black.

Bedbugs are similar in size to dog ticks, which can attach to the skin. Fleas are skilled jumpers and biters that can inflict up to 400 bites in one attack. Fleabites typically present with an erythematous papule bordered by a scarlet halo. Flea and tick bites typically stay itchy and irritated.² Tick bites are of primary concern because they can transmit infectious diseases like Lyme borreliosis, which may lead to the development of target lesions. The bite pattern of fleas is a non-follicular, grouped pattern of erythematous papules.³ Bedbugs do not inject fluid. They just aspirate blood so disease transmission is unlikely.

How To Address Bedbug Bites
In general, patients should wash all insect bites with soap and water. It is fortunate that most bedbug bites do not cause symptoms. Some bites, however, may irritate ankles and legs to a degree that requires reduction of local edema with ice or a cold pack. In addition, topical hydrocortisone creams and lotions for individual lesions may be necessary to control inflammation. For symptomatic relief, topical hydrocortisone, calamine or pramoxine can help to decrease pruritus. Patients should maintain good hygiene and avoid scratching to reduce the risk of secondary infection that may require antibiotics. Non-sedating oral antihistamines such as cetirizine (Zyrtec) 10 mg once a day or loratadine (Claritin) 10 mg once a day may be helpful for patients with troublesome itching.^1,4

Typical bedbug bites occur on the face, neck, arms and legs. When a reaction occurs, a 2.5 mm erythematous papule or wheal with a central hemorrhagic pruritic punctum can arise. More severe reactions can manifest as bullae that may ulcerate.¹ Occasionally, bedbug bites may become secondarily infected, triggering impetigo or cellulitis. Excoriated or impetiginized areas may take several weeks to heal. Excoriated or impetiginized areas may take several weeks to heal.

A “linear feeding” may occur as a single bedbug probes a patient multiple times, looking for a productive capillary. This can produce the so-called “breakfast, lunch and dinner pattern.”
Bedbugs typically arise in economically disadvantaged areas but can also occur in more affluent locations. They can move from room to room, and even spread throughout entire buildings. They are attracted by carbon dioxide and feed while the victim sleeps or is relatively still while watching a movie. It can take about five to 10 minutes for a complete meal.

Bedbugs can survive up to about a year without a blood meal. They also can survive cold winter temperatures. Although some studies have found hepatitis B and methicillin-resistant Staphylococcus aureus (MRSA) in bedbugs, and association with trypanosomiasis (Chagas disease), studies have not found bedbugs to be direct vectors for disease.¹ Naturally, patients with bedbug infestations may experience stress, anxiety and depression, which may need professional evaluation.  

A Guide To Bed Bug Eradication
Adhesive traps can help capture the insects. Heat or carbon dioxide-emitting traps can also help eradicate the insects.⁵ Small infestations of bedbugs are difficult to detect and one should suspect infestation if specks of feces or blood are present on linens, mattresses or behind wallpaper.⁶ In widespread infestations, bedbugs can produce a recognizable pungent odor.⁷

Eradication of bedbugs is difficult and control often requires professional pest management. Victims should refrain from attempting control measures on their own. Overzealous use of insecticides or heat treatments can be worse than the bites. Attempting self-eradication can lead to injury for the victim.

High temperature washing and drying is usually adequate to kill bedbugs in clothing or linens. Commercial equipment is required to heat rooms to lethal temperatures of 50°C (122°F) for 90 minutes. Some areas may require professional insecticide treatment.⁸ Although insect repellents are generally not effective against bedbugs, increasing concentrations of the common insect repellent DEET can cause bedbugs to take progressively smaller meals.⁹

Prevention involves careful visual inspection of hotel linens and mattress cords. Placement of luggage on a luggage rack and away from the bed is a good precaution. Careful examination of “used” items, such as garage sale items or items (especially bedding) from resale shops, for bedbugs or bedbug feces prior to bringing them inside the home is important.

It would be helpful for doctors to print out online bedbug information so the bedbug victum knows what to look for and understands the appropriate steps to eradicate the infestation. A local public health department should be able to help with efforts to limit the spread of bedbug infestations.

Dr. Bodman is an Associate Professor at the Kent State University College of Podiatric Medicine. He is a Diplomate of the American Board of Podiatric Medicine.

References

1. Goddard J, deShazo R. Bed bugs (Cimex lectularius) and clinical consequences of their bites. J Am Med Assoc. 2009;301(13):1358.
2. Elston DM, Kells S, Dellavalle RP, et al. Bedbugs. UpToDate. Available at https://www.uptodate.com/contents/bedbugs . Published August 5, 2015.
3. Vaidyanathan R, Feldlaufer MF. Bed bug detection: current technologies and future directions. Am J Trop Med Hyg. 2013;88(4):619-25.
4. Cleary CJ, Buchanan D. Diagnosis and management of bedbugs: an emerging U.S. infestation. Nurse Pract. 2004;29(6):46.
5. Thomas I, Kihiczak GG, Schwartz RA. Bedbug bites: a review. Int J Dermatol. 2004;43(6):430.
6. Centers for Disease Control and Prevention (CDC). Acute illnesses associated with insecticides used to control bed bugs--seven states, 2003--2010. Morb Mortal Wkly Rep. 2011;60(37):1269-74.
7. Kells SA, Goblirsch MJ. Temperature and time requirements for controlling bed bugs (Cimex lectularius) under commercial heat treatment conditions. Insects. 2011;2(3):412.
8. Kumar S, Prakash S, Rao KM. Comparative activity of three repellents against bedbugs Cimex hemipterus (Fabr.) Indian J Med Res. 1995;102:20.

For further reading, see “Diagnosing And Treating Insect Bites And Stings On The Lower Extremity” in the April 2015 issue of Podiatry Today.