A 15-year-old girl is brought to the office for a routine examination. Her mother is concerned that "she started developing breasts a few years ago but has not yet started menstruating." The patient's breast development began at age 12. She also recently had a "growth spurt" and has grown 8 cm (3.15 in) in the last year. She reports occasional fatigue, which her mother attributes to "staying up late to talk with friends" and multiple afterschool activities. The patient takes no daily medications or supplements and has no known allergies. She is not sexually active and does not use tobacco, alcohol, or illicit drugs. She eats a balanced diet with no restrictions. Vital signs are normal. Weight and height are in the 30th and 80th percentiles, respectively, consistent with growth percentiles from previous visits. Physical examination reveals a well-appearing, cooperative patient. The neck is supple with no thyromegaly. The breasts are sexual maturity rating 4. Cardiac examination reveals a regular rate and rhythm with no murmur. The abdomen is soft and nondistended with no palpable masses. Pubic and axillary hair are absent. Which of the following is the most likely diagnosis in this patient?
A)Androgen insensitivity syndrome
B)Constitutional delay of puberty
C)Functional hypothalamic amenorrhea
D)Müllerian agenesis
E)Normal pubertal development

Question

A 15-year-old girl is brought to the office for a routine examination.  Her mother is concerned that "she started developing breasts a few years ago but has not yet started menstruating."  The patient's breast development began at age 12.  She also recently had a "growth spurt" and has grown 8 cm (3.15 in) in the last year.  She reports occasional fatigue, which her mother attributes to "staying up late to talk with friends" and multiple afterschool activities.  The patient takes no daily medications or supplements and has no known allergies.  She is not sexually active and does not use tobacco, alcohol, or illicit drugs.  She eats a balanced diet with no restrictions.  Vital signs are normal.  Weight and height are in the 30th and 80th percentiles, respectively, consistent with growth percentiles from previous visits.  Physical examination reveals a well-appearing, cooperative patient.  The neck is supple with no thyromegaly.  The breasts are sexual maturity rating 4.  Cardiac examination reveals a regular rate and rhythm with no murmur.  The abdomen is soft and nondistended with no palpable masses.  Pubic and axillary hair are absent.  Which of the following is the most likely diagnosis in this patient?
A)Androgen insensitivity syndrome
B)Constitutional delay of puberty
C)Functional hypothalamic amenorrhea
D)Müllerian agenesis
E)Normal pubertal development

Quizplus · Accepted Answer

Explanation: 11ec2b69_c12f_d331_8f63_f352a7526639_MD0005_00 This patient most likely has androgen insensitivity syndrome, a disorder of sexual development characterized by phenotypical female features with a male (46, XY) genotype. This X-linked recessive condition is caused by a mutation of the androgen receptor gene, which makes peripheral tissues unresponsive to androgens despite normal concentrations produced by intact testes. androgen insensitivity syndrome Patients often present in adolescence with primary amenorrhea, defined as absence of menarche by age 15 if breast development is present or by age 13 if not. Breast development is typically normal in this disorder because excess testosterone is aromatized to estrogen. However, no pubic or axillary hair is present. Cryptorchid testes often reside in the inguinal canal or abdomen, as testicular descent is an androgen-dependent process. The uterus and fallopian tubes are absent, and the vagina ends with a blind pouch. Diagnostic workup includes pelvic ultrasound, karyotype, and testosterone level. A serum testosterone level in the normal adult male range is characteristic. (Choice B) Constitutional delay of puberty typically occurs in boys with short stature, delayed bone age, and a family history of late-onset puberty. It is a diagnosis of exclusion in girls, and is unlikely in this girl with asynchronous pubertal development (normal thelarche but no pubarche). (Choice C) Functional hypothalamic amenorrhea, often seen in athletes, is typically secondary to weight loss, increased exercise, or stress. Amenorrhea with delayed breast development is expected. (Choice D) Although the uterus is typically absent with Müllerian agenesis, ovaries are present and secondary sexual characteristics develop normally. It is less likely in this patient with no pubic or axillary hair. (Choice E) Amenorrhea at age >15 is considered abnormal, even if secondary sexual characteristics are present. Educational objective: Androgen insensitivity syndrome presents in phenotypical females with primary amenorrhea and absent pubic/axillary hair but normal breast development. Diagnostic features include an absent uterus but intact testes, a (46, XY) karyotype, and serum testosterone levels in the normal adult male range. References: Androgen insensitivity syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/20301602)

A 15-Year-Old Girl Is Brought to the Office for a Routine