Differential Diagnosis for a Loud and Continuous Crying Infant with Firm Hot Tender Bluish Inguinal Mass

• Single Most Likely Diagnosis
  • Irreducible Inguinal Hernia: This condition is highly likely given the description of a firm, hot, tender, and bluish inguinal mass. An irreducible inguinal hernia, especially if it has become incarcerated or strangulated, can cause severe pain and the described physical findings, leading to continuous crying in an infant.
• Other Likely Diagnoses
  • Testicular Torsion: Although less common in infants, testicular torsion can present with a firm, tender, and possibly bluish mass if the torsion is severe and compromises blood flow. The pain from testicular torsion can cause significant distress, leading to continuous crying.
• Do Not Miss Diagnoses
  • Appendiceal Torsion: Although rare, appendiceal torsion can mimic other abdominal or inguinal pathologies. It's crucial to consider this diagnosis due to its potential for severe consequences if missed, including necrosis and peritonitis. However, the presentation might be less typical for appendiceal torsion compared to other conditions.
• Rare Diagnoses
  • Other rare conditions such as a hydrocele or varicocele could potentially present with a mass, but these are less likely to cause the acute, severe symptoms described. Vascular malformations or tumors could also present as a mass but would be uncommon and might not fully explain the acute onset of symptoms unless there was a sudden change or complication.

Each of these diagnoses should be considered in the context of the infant's overall clinical presentation, and a thorough examination along with appropriate diagnostic tests should be conducted to determine the exact cause of the symptoms.