Other than a moderate anaemia there is very little in the blood of yaws which differs from the normal.

Peculiar Types of Yaws.—When yaws tubercles develop in the palms of the hands or soles of the feet we have a very painful and incapacitating condition resulting. The pressure of the thick unyielding epidermis on the tubercles beneath gives rise to marked pain, thus differing from tubercles on other parts of the body. Eventually these tubercles break through and the affected sole may have a worm-eaten appearance. The name “crab yaws” is a common one for such a condition involving the soles of the feet and is so-called from the difficulty in walking which has a resemblance to the locomotion of a crab. In some cases the yaws tubercles adjoin one another to form a circle enclosing unaffected skin. Such an arrangement of lesions is often described under the name of “ringworm yaws.”

Fig. 124.—Tertiary yaws. Clavus or Crab-yaws. (Johns Hopkins Bull., Moss and Bigelow.)

Diagnosis

Clinical Diagnosis.—Bromide eruptions may greatly resemble yaws but the history of the taking of the drug and the effect upon withdrawal should differentiate.

Syphilis and Yaws.—Degorce gives a very complete table of the points of difference between syphilis and yaws, some of the more important of which are the following:

YawsSyphilis
1. Primary lesion of soft consistency, or very little infiltrated, with granulating or pimply surface, situated almost invariably extragenitally, resembling the secondary lesions. Lymphadenitis not marked.1. Primary lesion infiltrated and indurated, with flat and smooth surface, ordinarily situated on the genital organs; often accompanied by abundant lymphadenitis. Phagedenic processes frequent.
2. Roseola resembling that of syphilis but rarer.2. Roseola present.
3. Secondary cutaneous lesions at first in the form of conical elevations of a light red color, not infiltrated at base, appearing in close groups. The lesions are similar to those of syphilis, namely, on the scalp in the form of encrusted papules; on thin-skinned regions in the form of ulcerating papules, and in the case of the palm of the hands and plantar surface of the feet, in the form of simple papules.3. Secondary cutaneous lesions papular from the first, dark red, infiltrated and fairly regularly scattered.
4. Circinate lesions with the edges more raised than in syphilis, covered with yellow crusts.4. Circinate lesions with pink edges, slightly raised, with fine scales.
5. On the face lesions of the same type, but more striking and with irregular projections.5. Seborrheic syphilides on the face.
6. Cutaneous lesions do not itch.6. Cutaneous lesions do not itch.
7. Perionychia similar to that of syphilis, but occasionally giving rise to pimply lesions.7. Perionychia present.
8. Alopecia has not been described.8. In syphilis, alopecia rather the exception.
9. Lesions in the buccal and pharyngeal mucosa often absent. No erythema. No typical mucous patches. Sometimes fissures at the angles of the mouth. The typical lesions are raised, pure white and occasionally covered with intact epithelium.9. Lesions in the buccal and pharyngeal mucosa are not numerous and are slight in degree. Erythema of the soft palate and pharynx occurs. Mucous patches. Ulcers of the lips and at the angles of the mouth.
10. Lesions with prominent edges or even pustular with yellowish crusts, occasionally also ulcerations resembling mucous patches.10. In the glans, prepuce or vulva, the lesions are more or less typical mucous patches.
11. Similar condylomata, but larger and more raised.11. Moist condylomata at the margin of the anus.