Shiny Skin and Subcutaneous Calcifications in a 13-Year-Old Adolescent Girl

Patient Presentation

  • Demographics: 13-year-old female.
  • History:
    • Chronic right knee pain (duration: >1 year).
    • Prior orthopedic diagnosis: 'extra cartilage of the knee' (1-year ago).
    • No follow-up due to COVID-19 pandemic.
    • Worsening of pain leading to difficulty bearing weight.
    • Use of crutches for 1 week.
  • Pain Description:
    • Characterized as stabbing, localized to the right knee.
    • Exacerbated by movement and activity.
    • Minimal relief with rest, unmanageable with ibuprofen.
  • Associated Symptoms:
    • Bilateral ankle pain.
    • Mild exertional dyspnea.
    • Progressive fatigue.
    • Decreased appetite and 6-lb (2.7-kg) weight loss in last 6 months.

Menstrual and Skin Symptoms

  • Menstrual History:
    • Menarcheal, regular periods for 8 months.
  • Skin Findings:
    • Red/purple discoloration of fingers with cold exposure.
    • Dry skin feeling 'tight', present for several years.
  • Review of Systems: Denies:
    • Fevers, night sweats, bone pain, myalgias, oral ulcers, visual disturbances, eye pain, orthopnea, gastrointestinal symptoms, chest pain, or swelling of hands/feet.
    • No recent illnesses, travel, or trauma.

Clinical Examination

  • Vital Signs:
    • Temperature: 98.6 °F (37 °C)
    • Heart Rate: 116 beats/min
    • Respiratory Rate: 20 breaths/min
    • Blood Pressure: 133/67 mm Hg
    • Oxygen saturation: 98% on room air.
  • Physical Measurements:
    • Height: 57 in (145 cm) (2nd percentile)
    • Weight: 119 lb (54 kg; 74th percentile)
    • BMI: 25.81
  • General Appearance:
    • Nontoxic but appears to be in pain.
  • Head and Neck:
    • Normocephalic without alopecia.
    • Moist mucous membranes; no oral ulcers/lesions.
    • Pupils equal and reactive to light, extraocular movements intact.
    • No erythema or conjunctival injection.
    • Neck examination normal range of motion without tenderness.
    • No thyromegaly or palpable lymphadenopathy.
  • Respiratory Exam:
    • Symmetrical air entry, clear breath sounds.
  • Cardiac Exam:
    • Tachycardic but normal S1 and S2, no murmurs or rub.
  • Abdominal Exam:
    • Soft, nontender, normoactive bowel sounds, no hepatosplenomegaly.
  • Muscle Strength Testing:
    • Bilateral upper extremities: 3/5 strength.
    • Bilateral lower extremities: 5/5 strength.

Examination Findings

  • Muscle Bulk/Tone:
    • Symmetrical in both upper and lower extremities.
  • Knee Exam:
    • Generalized tenderness and prepatellar crepitus noted.
    • Limited range of motion in flexion due to pain.
    • No warmth, erythema, or swelling of the knee.
  • Joint Range of Motion:
    • Full range of motion in bilateral hips without pain.
    • No tenderness, erythema, swelling or decreased range of motion in peripheral joints.
  • Skin Examination:
    • Hypopigmented, taut, waxy-appearing patches consistent with morphea on upper arms, chest, abdomen.
    • Bruised and discolored skin overlying the right knee, several subcutaneous immobile nodules, pustule-like lesions in various healing stages.
    • Palpable smaller nodules on right hand (thenar eminence).
    • Presence of sclerodactyly bilaterally.
    • Nailfold capillaries show increased tortuosity and some dropout.
  • Neurological Examination:
    • Intact cranial nerves, normal deep tendon reflexes, and normal sensation.
    • Gait examination limited due to right knee pain.

Initial Laboratory Studies

  • Blood Tests:
    • Complete blood count: indices within normal limits.
    • Comprehensive metabolic panel, inflammatory markers (CRP, ESR), blood culture and wound culture (draining pustule from right knee).
    • Serum electrolyte levels and renal function normal except for serum phosphate: 4.9 mg/dL (RR: 2.5–4.6 mg/dL).
    • Erythrocyte sedimentation rate (ESR): 16 mm/h (RR: 0–20 mm/h).
    • C-reactive protein (CRP): 0.14 mg/dL (RR: 0–0.74 mg/dL).
    • Wound culture Gram-stain: no organisms present.
  • Cardiac Monitoring:
    • ECG after pain treatment: heart rate 97 beats/min, no ST changes.
  • Imaging:
    • Right knee X-ray reveals extensive soft tissue calcification anteriorly.
    • Admittance to inpatient pediatric unit for further evaluation.
  • Consultations: Orthopedics and rheumatology were consulted.
  • Further Imaging:
    • MRI of right knee confirms extensive soft tissue calcifications.
    • Orthopedic surgeon performs excisional biopsy for diagnostic clarity.

Biopsy and Results

  • Tissue Biopsy Findings:
    • Multinodular deposits of amorphous material in skin and subcutaneous tissues, no malignant features.
  • Pulmonary Function Tests:
    • Forced expiratory volume in 1 second: 79% predicted (RR: ≥80%).
    • FEV1/FVC ratio: 0.86 (RR: ≥0.7).
    • Adjusted diffusion capacity for CO: 71% of predicted (indicating mild restrictive lung disease pattern).
  • Further Laboratory Tests:
    • Creatine Kinase: 1568 U/L (RR: 22–232 U/L)
    • Lactate Dehydrogenase: 413 U/L (RR: 91–200 U/L)
    • Aldolase: 46.4 U/L (RR: 3.3–9.7 U/L)
    • Aspartate Aminotransferase: 194 U/L (RR: 15–40 U/L)
    • Alanine Aminotransferase: 98 U/L (RR: 0–55 U/L)
    • Uric Acid: 4.7 mg/dL (RR: 4–8 mg/dL)
    • Alkaline Phosphatase: 96 U/L (RR: 70–490 U/L)
    • 25-Hydroxyvitamin D: <7 ng/mL (RR: 30–100 ng/mL)
    • Parathyroid Hormone: 40.8 pg/mL (RR: 12–88 pg/mL)
    • Antinuclear Antibody Titer: 1:640 in nucleolar pattern.

Differential Diagnosis

  • Considered Conditions:
    • Juvenile dermatomyositis (JDM), juvenile systemic sclerosis (jSSc), overlap syndrome, mixed connective tissue disease (MCTD).
    • Tumoral calcinosis: soft tissue calcium phosphate deposits were considered.
    • Infectious causes unlikely due to absence of fevers, negative wound cultures, and normal inflammatory markers.
    • Synovial chondromatosis less likely due to lack of joint effusion and presence of thenar lesions.
    • Disorders of parathyroid and vitamin D metabolism unlikely due to normal parathyroid hormone levels despite hyperphosphatemia.
    • Malignancies to be ruled out via tissue biopsy.
  • Juvenile Dermatomyositis:
    • Idiopathic inflammatory myopathy, affects skin and muscle.
    • Characterized by activation of complement leading to muscle ischemia.
    • Typical features: proximal muscle weakness, skin findings (heliotrope rash, Gottron's papules), elevated muscle enzymes.
  • Juvenile Systemic Sclerosis:
    • Progressive disease affecting skin and viscera.
    • Key features: Raynaud phenomenon, morphea, sclerodactyly, capillary abnormalities, arthritis, calcinosis.
    • Antinuclear antibody highly sensitive, with further autoantibodies aiding in diagnosis.

Final Diagnosis

  • Overlap Syndrome:
    • Combination of JDM and jSSc.
    • Characterized by symptoms and laboratory findings meeting criteria for both diseases.
  • Rheumatologic Overlap Syndromes:
    • Defined as meeting classification criteria for multiple connective tissue diseases.
    • Common examples include MCTD, with features of systemic lupus erythematosus, systemic sclerosis, dermatomyositis, polymyositis, and rheumatoid arthritis.
  • Incident Rates:
    • Rare in the pediatric population, JDM incidence: 2-4 per million; jSSc incidence: 0.27 per million children.

Treatment and Management

  • General Treatment:
    • Based on conventional treatments for individual autoimmune diseases.
    • Systemic corticosteroids to address inflammation in muscle and skin.
    • Intravenous immunoglobulin G as an adjunct for immunomodulation.
    • Methotrexate utilized as a corticosteroid-sparing agent.
  • Organ Involvement Assessment:
    • Critical for guiding treatment and prognostication.
    • Ongoing surveillance to track progression and potential complications.
  • Patient Course:
    • Complicated biopsies requiring skin grafting due to poor healing.
    • Delayed treatment to facilitate healing.
    • Initiated Vitamin D supplementation (50,000 IU weekly for 8 weeks) due to deficiency.
    • Readmission after 3 months for worsening symptoms; regimen included corticosteroids, methotrexate, mycophenolate mofetil, and intravenous immunoglobulin G.
    • Improvement in muscle enzyme levels and functional status noted.
    • Subsequent physical therapy showed progress in joint range of motion and skin condition.

Clinical Lessons

  • Subcutaneous Calcinosis:
    • Presents with a wide differential and may indicate underlying rheumatic diseases.
    • Rheumatologic overlap syndromes require accurate diagnosis to effectively treat combined disorders.
    • Mixed connective tissue disease characterized by features of multiple connective tissue diseases and presence of anti-U1-ribonucleoprotein.

References

A wide range of references exist for more in-depth information on the clinical features, diagnoses, and treatment options for injuries and conditions observed in this case.